Ai Cornell University Library HV 676.A2T77 Safety in the machine shop 3 1924 002 407 611 ;:^A^JlTY IN THE Machine Shop I il' HV 676 it T 77 THE TRAVELERS INSURANCE COMPANY HARTFORD, CONNECTICUT Reasons for selecting The TRAVELERS tor Workmen's Compensation and Employers' Liability INSURANCE AND SERVICE It is 1 It He mana CORNELL UNIVERSITY ly It is 1 LIBRARY It pr minis of ac( NEW YORK STATE SCHOOL OF INDUSTRIAL AND LABOR RELATIONS d- 3n ItisE ^^^ se who ] MiHii^m, m oppo] Mr^pM ae comp bleq THE GIFT OF Sl- T fo Ij. a. Emerson The Ti »ANY THE Tl ?ANY . 1 , Lines written by The TRAVELERS include LIFE, ACCIDENT and HEALTH, GROUP, WORKMEN'S COMPENSATION, EMPLOYERS' LIABILITY, PUBLIC LIABIL- ITY, AUTOMOBILE, AIRCRAFT, STEAM BOILER, ENGINE, ELEVATOR, BURGLARY and PLATE GLASS Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924002407611 SAFETY IN THE Machine Shop THE TRAVELERS INSURANCE COMPANY HARTFORD, CONNECTICUT 21452. 3-3-'20. G~f\/k/ Copyright, 1920, by The Travelers Insurance Company, 4 Hartford, Connecticut hi PREFACE The present booklet is based upon a series of articles that have appeared from time to time in The Travelers Standard, but the original matter has been extensively revised, and additions have also been freely made wherever they appeared to be desirable. No attempt has been made to cover all the hazards that occur in the machine shop, but special attention has been paid to those which are responsible for the major part of the serious accidents that occur. The advice that is given in connection with certain specific machines should be considered applicable to all other machines in which like sources of danger occur. The principles relating to the guarding of gears on lathes apply equally well, for example, to the guarding of similar gears on machines of other kinds. In discussing physical safeguards we have not at- tempted, in every case, to give the complete specifica- tions that should be followed in order that the needed guard may be considered to be standard and wholly satisfactory. To do so would involve tiresome and un- profitable repetition, which would not be consonant with the main purpose of this booklet. We have en- deavored, instead, to call attention to the chief sources of danger, and to give general counsel with regard to the elimination or control of these sources. The Engineering and Inspection Division of The Trav- PROPERTY OF LIBRARY NEW YORK STATE SmU INDUSTRIAL AND L^BOR HEUTIONS CORNELL UNIVERSITY 40130 4 PREFACE ELERs Insurance Company publishes an exceedingly- useful pamphlet entitled "Industrial Standards", which is copiously illustrated and which describes physical safeguards of many kinds, giving all needful details concerning the way in which these safeguards should be made and installed. The reader who desires more specific details in connection with the construction and erection of safeguards should therefore refer to that pamphlet. The Travelers Insurance Company, Hartford, Connecticut. CONTENTS. Section I. The Development of The Modern S The small shop, The division of labor, Skilled and unskilled labor, Safety and welfare work, New and old machines, . 9 9 10 11 13 Section II. The Use of Cranes: In general, ..... Stairways, foot-walks, and safeguards. Operation of cranes, Gongs, .... Signals, .... Chains, hooks, and slings. Repairs, .... 15 IS 17 21 21 22 24 Section III. The Spacing of Machines: Importance of good spacing, . . . . Obstruction of floors and aisles, Trucks, . . . . . , Systematic spacing and the use of "dead lines," 26 28 30 31 Section IV. Shafting and Belting: Importance of proper safeguarding, . Relation of the safeguards to the lay-out of the shop, Standards for belt guards, Shifting belts. Dressing belts. Chain drives. Fall of shafting. Splicing belts. An accident involving belt clips, Overloading belts, . Oiling shafting, Protection of shafting, Keys, . Periodic inspections, 33 39 40 44 47 49 49 50 53 55 56 58 59 59 Contents Section V. Individual Motor Drive Advantages of individual motor drive Electrical accidents, Grounding, .... Guarding motors and conductors. Switches and controllers.. Starting panels, Open knife switches. Fuses and circuit breakers. 61 64 67 67 69 70 71 71 Section VI. The Safe Operation of Lathes: Tools, ..... Eye protection. Filing Set screws and other projections, Belts, Gears, ..... Miscellaneous suggestions. 73 73 75 76 77 79 79 Section VII. Forging and Hammering: Early forging, .... Burns and sparks, .... Tools, ...... Power hammers, .... Pressing and trimming operations, . Cyanide, ..... 81 81 82 82 85 86 Section VI IT. The Press- working of Metals: Development of press-working. Description of presses. Ram bearings, Springing and lost motion. Inspection and adjustment. Selection of a press. Feeding presses, Safeguards, .... Relation of safeguards to production, Reliance upon safeguards. Order and discipline, Illumination, .... Treadles, .... Miscellaneous suggestions. 87 87 88 90 90 92 92 95 98 99 100 101 102 103 Section IX. Automatic Machines: Development of the automatic machine. Handling the stock, 105 108 Contents General hazards, .... Recovery of cutting oil, . Section X. Infection From Cutting Oils: Cutting oils in general, . Soluble oils, .... Infection and its causes. Comparison of aqueous oils and lard oil, Waterproof dressings, Sterilization by heat. Use of antiseptics, . Covers for tanks, . Individual circulating apparatus. 109 113 115 115 116 118 119 120 122 124 124 Section XI. Grinding, Polishing, and Buffing: General considerations, . Abrasive materials. Grinding, Polishing wheels, Buffing wheels, Steel-center wheels. Polishing and buffing lathes. Dust removal. Injuries, Eye-protectors, Speed of wheels, Wheel-dressing, Glue, 127 129 129 130 132 132 132 134 136 136 136 137 138 Section XII. Hand Tools: Hand tools in general. Files, Wrenches, Chipping, Burred tools, . Sledges, Inspection and care of tools, General precautions. The lesson, Section XIII. Illumination: The fundamental principle. Daylight illumination. Local units in artificial lighting, Specular reflection. Need for expert advice, . 142 142 143 144 144 145 145 146 148 149 149 152 154 156 Contents Localized general illumination, Portable lights, .... Flexibility of the localized general system, Care and maintenance, ... Section XIV. The Employment of Women Limitations of women, Selecting the women. Training the women. Bringing the women into the shop, . Uniforms, ..... Special aspects of the safety problem. Supervision and discipline, Hours of labor, .... Sanitation and general welfare. 158 158 159 160 161 163 164 167 168 171 174 176 179 SAFETY IN THE MACHINE SHOP I. THE DEVELOPMENT OF THE MODERN SHOP. The Small Shop. Before the intense industrial development of the last few decades, the machine shop, like most other shops, was often a pretty small affair. It was usually founded by a capable and versatile me- chanic, who established himself somewhere or other, and did all the different kinds of work that came in. With increase of business he hired other men to help him, and perhaps took in a few apprentices ; but for years the shop was still small enough to have a comparatively simple organization. There was also close and friendly cooperation between the employer and his employees, on account of the intimate personal relation that nat- urally existed between them. The apprentices learned their methods under the owner's immediate supervision. They caught the spirit of the shop, and the professional pride that the older men took in their work and in the exercise of their skill was stimulating to the younger ones, and contagious. Differences of all kinds were easily adjusted, because the parties concerned were near enough together for each to see the other's point of view. The Division of Labor. The industrial expansion that changed the "one-man shop" into a larger one, and 10 THE TRAVELERS INSURANCE COMPANY transformed the "help" into human machines, was a deeply-rooted, world-wide movement, which was forced upon us by competition, by the introduction of ma- chinery in place of hand work, and by the inevitable development of the principle of the "division of labor." By the latter is meant the division of the manufacture of any article into a considerable number of small processes, each more or less complete in itself, and the regulation of the work so that every man is assigned to some one of these minor processes, in which he becomes a "specialist," devoting all his energy and attention to the repeated performance of a single simple task, — over and over and over again. This "division-of-labor" system undoubtedly tends to promote efhciency, but it also tends to do away with the all-around mechanic, and from this point of view its development is unfortunate. In these present days of intense activity in machine shops, the tendency to work each employee along a narrow line of specializa- tion often makes it necessary to instruct and train a new man in the particular operation that he is to per- form, before he can be set at work; because although he may have acquired marked skill in some special direction in one factory or shop, it is by no means cer- tain that he will find employment at the same identical job in the next place where he looks for work. Skilled and Unskilled Labor. Men having an exceedingly limited knowledge of the machinist's trade must be employed to-day, — partly because skilled me- chanics cannot be had in sufficient numbers, and partly because the untrained man costs less than the trained one. Machines are made to perform the various oper- ations as automatically as possible, and the men who DEVELOPMENT OF THE SHOP 11 attend them merely have to see that the machines are operating properly, and that they are kept supplied with raw material. A man having even a small mechanical bent can often be trained in two or three days to attend an automatic machine well enough to turn out a very good product ; but a man of this sort cannot be expected to know enough about machinery to properly appreci- ate the hazards to which he is exposed, and this fact has a large bearing on the accident-prevention problem. It is natural to ask what we shall do in the near future, for master machinists with a knowledge of the subject broad enough to serve as foremen, superinten- dents, and managers. It is not easy to give a full answer to this question in a few words, but it is fair to say that the young man of to-day can gain this broad knowledge if he goes after it. But he must have perseverance and stamina. In this respect, however, he is not upon a wholly different basis from the young men of an earlier generation, because there has never been any royal road leading to real competence as an all-around machinist. Technical schools are excellent, and apprentice systems are also helpful ; but the young man who wants a broad and thoroughly sound know- ledge of the machinist's trade must get it now, as always, by hard knocks and diUgent application. He will probably get it best in a country repair shop, where no two jobs are alike, and the available tools are few. He will have to think hard in a place like this, and exercise his ingenuity to the utmost. He will have to ^^ strive with things impossible ; Yea, get the better of them." Safety and Welfare Work. The larger and more complicated an enterprise grows, the harder it becomes 12 THE TRAVELERS INSUB^NCE COMPANY for the mind of any one man to encompass it and weld it into a perfect unity of organized purpose. In the history of every big machine shop there came a time when the employer could no longer know all his employ- ees intimately, and keep in personal touch with their needs and interests. His time became entirely taken up by the broad questions of general efficiency and policy, and he was forced to appoint foremen to carry out his orders and do all the actual and immediate supervising. As the business continued to grow, the employees became still more numerous and the organi- zation still more complicated, until a point was perhaps reached at which the man at the head was known to the rank and file only by sight and by reputation. When this state of things had come to pass, the ownership of the plant was probably vested in a corporation. Now a corporation is a bloodless and sometimes (if we may believe the newspapers) a soulless body, and a manu- facturing industry that is owned and operated by a corporation is likely to develop one-sidedly (unless special effort is made to counteract such a tendency), with too large a proportion of its efforts devoted to the development of mere efficiency, and too small a pro- portion to the care and protection of the workers. The man on the job is not a machine, and it is a serious mistake to treat him as one. We are glad to note that this fact is now pretty well recognized, and that the management of our industries is being modified accordingly. A competent man in good working condition is a valuable asset, and it is a plain matter of sound business policy (apart from all humanitarian considerations) to provide for his safety and welfare. Good sanitary arrangements (including under this term DEVELOPMENT OF THE SHOP 13 ventilation, lighting, toilet facilities, and all other things that directly promote and conserve the health and reasonable comfort of the workers) are exceedingly important factors in the shop organization, and they have a marked influence upon both safety and produc- tion. The matter of promoting safety and welfare work, in a large plant in which the administrative officials and the rank and file of the workers are practi- cally strangers to one another, calls for special study. The Engineering and Inspection Division of The Travelers Insurance Company has published a special booklet on this subject, and will be glad to send it to any executive who may wish to avail himself of the suggestions that it contains. It is called "Organization in Safety Work." New and Old Machines. Owing to the great pres- sure under which our machine shops, as a class, have been working in the recent past, they have been forced to make use of more or less machinery not altogether appro- priate to the purposes to which it has been applied. Sometimes it has been necessary to buy second-hand machinery, and remodel it or rebuild it in certain re- spects, to adapt it to new uses. Machinery that is worn out, or that is rebuilt to serve new purposes, is not likely to be as safe as machinery that is in first-class condition, and that was originally built for the exact service to which it is to be put. Furthermore, a busy modern shop is often forced to make use of machines of old design, and to work them up to their full capacity. This manifestly has an important bearing upon the accident problem, because the machines that are now put out by the best builders are constructed with far greater regard for safety than those that were built even a few years ago. 14 THE TRAVELERS INSURANCE COMPANY All these matters, and many others that also bear on the safety of the men, should be carefully considered at all times, and in plants of every nature; but we feel that there is special reason for giving them the fullest attention, at the present day, in our overworked machine shops. II. THE USE OF CRANES. In General. Cranes of various types are used in the machine shop, but most of the heavy work is done by electrically-operated traveling cranes. The sugges- tions that follow therefore relate mainly to that type, although many of them are applicable to all cranes, and to hoisting devices of other kinds. Stairways, Foot-walks, and Safeguards. A sub- stantial stairway or ladder should be provided at one end of the crane runway, to provide access to the crane cab or cage; and when two cranes are operated on the same runway, stairways or ladders should be installed at both ends of it. The cranemen should always use this means of entering and leaving the crane cages. Every crane cab should be inclosed to a height of at least 42 inches on all sides, except where entrance is actually effected. The inclosure should preferably be of sheet metal or expanded metal, or of heavy, woven- wire mesh. If railings are used there should be an in- termediate rail midway between the top rail and the floor of the cab, and a six-inch toe-board should also be installed. A stairway or a ladder should always be provided for passing from the cab to the top of the crane bridge. This should be substantially built, and properly protected so that the crane operator or re- pairman will be in no danger of falling when he uses it. A foot-walk should be constructed along the bridge of the crane, or on both sides where the width 16 THE TRAVELERS INSURANCE COMPANY of the bridge demands. This will give easy and safe access to the trolley in any position, and to any part of the bridge. The construction should be substantial, and the width must be sufficient to provide ample room for passage. Double railguards 42 inches high should be erected along each foot-walk, and six-inch toe-boards should also be provided. Whenever possible, a substantial walk should be installed beside the crane runway, and this should be protected by strong railings and toe-boards along its entire length. All traveling cranes should be equipped with spring bumpers or oil bumpers, and suitable stops should be installed at each end of each rail of the runway. All gears on the trolley and other parts of the crane should be completely incased, and no one should be allowed on top of the crane while it is in motion. A stout sheet-metal pan, or a substantial floor, should be provided under the trolley, to catch any parts that may work loose, and to prevent them from falling upon employees below. This pan or floor should be solid except for the cable openings. Guards, fenders, or brushes should be attached in front of the bridge and trolley wheels, to remove any obstructions that may be upon the tracks, and to prevent injury to persons who may be working in such positions that their hands or feet might be crushed by the wheels. All electrical wiring should be installed in conduits; and it is particularly important that hoist-limit stops be provided, in all cases, both for the main and for the auxiliary hoists. In the best crane practice the hoist-limit stops employ dynamic braking to check over-travel and to assist in lowering loads. To prevent THE USE OF CRANES 17 the crane from being operated by unauthorized persons, or while repairs are being made, there should be a safety switch in the main line, mounted above the cab where it can be conveniently reached from the foot-walk. This switch should be fitted with a lock so that it can be secured in the open position, and the key should be only in the possession of the crane oper- ator or the head repairman. Woodwork should not be used about a crane, be- cause it is likely to become oil-soaked, and it is then exceedingly combustible. If it should take fire and the craneman, in order to make his escape, should run the crane to the stairway, the time required for this purpose might increase his danger quite materially, and the motion of the crane would also tend to in- crease the fire. If, on the other hand, he tries to leave the crane in any other way than by the regular stair- way, he will be exposed to hazards of other kinds, and these will be accentuated by his haste. Keep all tools, oil-cans, and waste in a closed metal box securely fastened to the crane or to the runway at some convenient point. Operation of Cranes. Careful, watchful, intelli- gent, and trustworthy crane operators, floormen, and repairmen, can do a great deal toward preventing accidents, and only such men should be employed about cranes. The following suggestions relate to the work of these men, and if faithfully followed will be the means of promoting safety in a marked degree. During the ordinary operation of an electric crane the craneman should never leave his cage without making sure that all the controllers are in the off posi- tion, and that the main switch is open. Before he 18 THE TRAVELERS INSURANCE COMPANY leaves the crane the safety switch should also be locked open. If the electric current should be shut off at any time, the same precautions should be observed; and before closing the main switch, when about to resume work after an interruption due to any cause whatsoever, the craneman should again make certain that all the controllers are in the off position. When about to lift a load, the motor should be run at low speed until the slack in the chain or cable has been taken up, after which the controller handle may be advanced slowly from point to point to in- crease the speed. Before a motor is reversed it should be brought to a full stop, except when an accident can be averted only by disregarding this advice. When handling a heavy load the craneman should hoist it a few inches above the floor, and then, before proceeding further, he should assure himself that it is properly balanced and that the slings are secure, and should also test the brakes to make sure that they will hold the load safely. If there is any doubt whatso- ever about the safety of the operation, the load should be lowered and the slings or brakes adjusted, or other necessary measures taken to avoid danger. It is also desirable, at the beginning of each shift, to test the foot brakes and limit switches thoroughly. It is extremely important, at all times, to "spot" the trolley directly over the load to be hoisted. Failure to do this will cause the load to swing sidewise as soon as it is clear of the floor, and men or objects near by may be struck by the load. Loads should be raised high enough to give proper clearance above men and objects on the floor, but they should not be carried for any considerable dis- THE USE OF CRANES 19 tance at an unnecessary elevation. So far as possible, the craneman should avoid transporting loads directly over workmen. Special care should be exercised to keep loads under control when lowering them, and the speed should always be restricted to a reasonable and safe limit. Some definite person must be held responsible for the selection of the chains and slings that are used for hoisting, and for making suitable hitches about the loads. If the shop is large enough to employ a special floorman, these matters may well be left to him, be- cause he is necessarily familiar with the constantly- changing conditions, and he should therefore be able to select the proper sling quickly and intelligently. More- over, experience will have taught him the best method for attaching the sling, or for hooking on to the load. If no special floorman is employed, this part of the work should be supervised by a specially assigned fore- man, or by a skilled hooker-on. When applying the hook to the load, and when holding the hook in place while the slack is being taken up, the hooker-on should be careful to avoid having his hands caught and crushed between the sling and the load. Hooks with safety handles may be had, and these add greatly to the safety of the men when hooking up. If safety handles are not provided, pieces of wood notched at the end may be used with advantage for holding the hooks in place, — the notch being pressed against the hook to prevent it from moving before the tension comes on it. When the hooks or slings are in place and the slack has been taken up, the workmen should immedi- ately move back several feet from the load. When a load is being deposited- all persons should keep at a safe 20 THE TRAVELERS INSURANCE COMPANY distance while the sHngs are being withdrawn from under it, because the sUngs may snap out suddenly, or may catch on the load and tip it over. When slacken- ing-off the hoisting cables the hooker-on should avoid pulling down on the inrunning side of the block, be- cause his fingers may be caught between the sheave and the cable and be cut off or badly crushed. It is far safer to grasp the outrunning side, and pull up and away from the sheave. Safety in this work is promoted by inclosing the block to which the hook is secured. The crane operator should never allow chains, slings, cables, or hooks to drag along the floor, and he should never start the crane carriage or trolley until all such appendages are entirely clear. Even in the short distance that the crane might travel before they leave the floor, the slings or hooks might become caught on some obstruction and cause an accident. No one should be permitted to ride on a load or on the crane hook; and if the craneman observes a viola- tion of this rule he should stop the crane and refuse to move it until the person who is riding is in a safe place on the floor. In a busy shop the craneman must be specially alert, and his attention must be given, unremittingly, to following the various operations on the floor, taking the signals from the floorman, and controlling the move- ments of the crane. Before an inexperienced man is permitted to take charge of a crane, he should be thoroughly trained in the work by a careful, well-qualified craneman, who should see that he becomes familiar with the operating mechanism, and skilled in the manipulation of the various levers and controls. THE USE OF CRANES 21 Gongs. A signal gong, operated by hand or foot, or electrically, should be part of the equipment of every crane, and should be rung when the crane is started, and as frequently thereafter as may be necessary Sometimes the gong is actuated by the mechanism that moves the crane, so that the warning signal is sounded automatically and continuously so long as the crane is moving. The objection to this method is that the sound of the gong is likely to become so familiar that its value as a warning of danger will be lost and the men will give little heed to it. Furthermore, the gong should always be treated as an extra safeguard, and no other safety precaution should be omitted or allowed to fall into disuse merely because the gong is used, nor should vigilance and caution be relaxed in any respect whatever. Signals. Some person should be specially desig- nated to transmit to the craneman the signals for mov- ing the loads, and the craneman should disregard signals given by other men. The signalman should stand in plain view of the craneman and should take care to give all his signals clearly. A definite and unmistakable code of signals, consisting of motions of the hands and arms, should be arranged. Signals given orally are unsatisfactory and unsafe, not only because it is often difficult to distinguish them with certainty unless the shop is quiet, but also because the sound of loud voices will always distract the attention of other men from their work. When a load is being transported some person designated for this purpose should always walk in front of it to warn workmen who are in danger of being struck by it, and he should also see that the load is carried high enough to clear all obstacles in its path. 22 THE TRAVELERS INSURANCE COMPANY because the craneman, on account of his location, some- times finds it hard to judge the height of the load correctly, and a mistake in this respect may be at- tended by serious consequences. Chains, Hooks, and Slings. Chains and hooks should be carefully inspected at regular intervals, and they should also be annealed from time to time by competent workmen who thoroughly understand the art of annealing, and who know how to secure the results that are desired. Particular care should be taken with hooks in this respect, because a hook, when properly annealed, should gradually yield or straighten if subjected to a serious overload, and thus give warning of danger; whereas if it is not properly annealed, and therefore hard, it is likely to snap off suddenly, without warning. Chains and hooks should be inspected with care immediately after annealing, because they are then cleaner than at other times, and hence any existing defects or flaws in them may be detected with greater certainty. All chains and hooks should be numbered, and a careful record should be kept of the inspections and annealings. Hoisting chains are particularly liable to failure through fatigue or over-strain, on account of the severe treatment to which they are frequently sub- jected; and they should therefore be examined minute- ly, and link by link, to detect insecure welds and slight cracks or other defects. Chain slings should never be crossed or twisted when placed around loads, and every chain that is to be used as a sling should be made of the highest quality of wrought iron. All chains should be oiled frequently, to prevent rusting. Forged hooks, or laminated hooks made of steel plates securely riveted together, should be used in pref- THE USE OF CRANES 23 erence to those made of cast steel. Hooks are some- times subjected to severe abuse by workmen who try to force them into position by striking them with heavy iron bars or other implements. This is a dan- gerous practice, and should be strictly prohibited. Wire-rope slings, when well made, give better service than chain slings, not only because they are stronger, weight for weight, but also because deterior- ation is usually indicated by broken strands that are readily discoverable by an experienced and qualified inspector. Wire-rope slings are pliable, and may be adapted to almost every use. They should be kept in good condition, and to prevent rusting and unnecessary wear from friction they should be treated with oil or with a good cable lubricant prepared specially for the purpose. A sling should never be allowed to rest directly against the sharp corners of a heavy casting or other similar object, but should be protected by wooden corner-pieces, or by pads of burlap or other soft material. Every sling, whether composed of a chain or a rope, should be long enough not only to surround the load it has to support, but also to leave a considerable space between the sling and the upper surface of the load. The oblique parts of the sling, which lie above the load and join it to the hook (or to the point where the sus- pension first becomes vertical) should never be so flat as to make an angle of less than 45 degrees with the ground. This precaution is highly important, but it is often overlooked or neglected, because the men do not realize that the stress on the ends of a sling is greater, the flatter (or more nearly horizontal) they lie. When 24 THE TRAVELERS INSURANCE COMPANY the ends are inclined at an angle of 45 degrees, the stress upon each of them is about 41 per cent, greater than it would be if the ends were vertical; and if the sling is so short that it barely goes around the load and has but little slack, the stress upon it may be very great indeed. We strongly advise that all slings, when not in actual use, be kept under lock and key and placed in charge of some responsible person who knows their condition and is competent to select safe and appro- priate slings for every occasion. They may be stored in the tool room or supply room, for example, and be in charge of a qualified foreman. Repairs. Hoisting apparatus of every kind should be inspected frequently and thoroughly, and all parts that are defective in any way should be promptly re- paired or replaced. The man charged with the oper- ation of the apparatus should not attempt to make repairs or adjustments, however, unless the shop is a small one, where this constitutes a part of his recog- nized duty. Under all other circumstances he should immediately report to the foreman or repairman, in order that the job may receive attention in the proper way. If the defect is serious enough to constitute a possible source of danger, the apparatus should not be operated until the necessary repairs or adjustments have been made. A crane that is to be repaired should be moved to one end of the runway or to some other point where it will cause the least interference with the movements of other cranes. The controllers and the main and emer- gency switches should be placed in the off position be- fore starting any repair work on cranes, and the safety THE USE OF CRANES 25 switches should be locked, or the fuses removed, to prevent any movement of the crane," and to avoid accidental short circuits that might result in injury to the repairmen. Suitable warning signs should be placed on cranes that are undergoing repairs, and buffers or rail stops should be clamped to the crane rails a few yards in front of the disabled crane when others are operated on the same runway. If practicable, a suitable floor area directly underneath the disabled crane should be roped off or inclosed in some other way, to prevent acci- dents that might be caused by tools or other objects falling from the crane. Similar precautions should be taken when men are at work on the runways, and red flags or other warning devices should be placed at both ends of the section undergoing repairs. III. THE SPACING OF MACHINES. Importance of Good Spacing. The demand for space suitable for manufacturing purposes, that is favorably located with respect to transportation facili- ties and the labor market, is almost always in excess of the supply. The manufacturer whose plant is so located that he has little or no expense for cartage of raw material or finished product, and at the same time has a supply of competent labor to draw on, has a decided advantage over a rival who is less favorably situated in these respects. The purchase price, or rental value, of a factory site is governed almost entirely by its location, and it is natural and wise for a manu- facturer to economize his space as much as possible, when a high-priced location is selected. This principle should be carried out with discretion, however, because many factors should be considered, aside from the original cost, before a definite plan or layout is adopted. Manufacturers often handicap themselves by crowding the machines together and limiting the aisle spaces, in the belief that greater economy and produc- tion will be gained thereby. There is certainly no advantage, however, from a production standpoint, in placing machines so close that the workmen interfere with one another. If the men are paid by the day they are likely to stand idle while the operation of a near- by machine interferes with their work; and where the piecework system prevails, each employee, knowing that THE SPACING OF MACHINES 27 his wage will depend upon his production, is likely to continue his work in spite of difficulties and dangers to which he may be subjected. His movements inter- fere with his neighbors' work, just as their movements interfere with his own; and where the crowding is ex- cessive the likelihood of accident may be very great. Serious results often follow from trifling causes, and a slight push may cause a workman to thrust his hand, arm, or foot into some moving part of the machinery, and be badly injured. To afford adequate protection to the workmen, the machines should always be properly separated from one another, and they should also be set at safe dis- tances from walls, posts, and other fixed parts of the building. Inadequate spacing is specially dangerous in connection with machines that turn out work of con- siderable length, or into which long, pieces of raw mat- erial are fed. The operator of each machine or group of machines must devote his attention to his own work, and so may be struck unexpectedly, and injured, by a bar or other object projecting from a machine near by. Under some circumstances one end of a bar of this kind may be caught in an unprotected gear or other moving part of the next machine, and be suddenly transformed into an erratic, revolving flail, or twisted or broken into flying pieces. In either case the chance of injury to the employees in the immediate neighborhood is great. The following conditions were observed during an inspection visit in a shop in which coal-mining drills are manufactured. On the same floor certain machines are used to sharpen one end of the drills, and others are 28 THE TRAVELERS INSURANCE COMPANY used to square up the opposite end, to fit the crank. Most of the drills are not over three feet long, and the machines are spaced so that work on drills of this length can be carried on upon all the machines at once, without interference. Sometimes, however, drills from four to six feet long are made by the same machines, and it is then necessary to work in a space which, al- though ample for making three-foot drills, becomes altogether too crowded when six-foot drills are sub- stituted. The operator, intent on the work at one end of the drill, is likely to overlook the fact that the other end is dangerously close to his neighbor and his neigh- bor's machine, on the right, while the drill of the workman on the left bears the same relation to him. Under these conditions there is an ever-present danger of injuring a fellow- worker at the next machine, or one walking along the aisle. The principle here noted in connection with work of one special kind applies also to many other industries, and should not be forgotten. Obstruction of Floors and Aisles. It is seldom that machines are crowded together, when wide aisles are provided at the same time. Limited machine-space and limited aisle-space usually go together, and in such cases there is rarely sufficient space, near the operators, for the safe storage of material or finished product. Furthermore, the operators usually take little care to arrange the pieces in orderly fashion, but simply let the material lie wherever it falls. There is seldom room for trucks, or for a sufficient number of trucks to serve all the machines. One of two dangerous conditions will then prevail: — either there will be excessive piling of material in the already crowded space, or there will THE SPACING OF MACHINES 29 be a constant procession of workers bringing in raw material and removing finished product. When piles of small castings or of other finished or unfinished material lie on the floor of a shop, some few of the pieces almost invariably become separated from the others, and persons passing by often stumble over them. A simple fall upon the floor may cause a bad injury, and the likelihood of a serious result is greatly increased when a man who has tripped over one of these objects falls in the direction of a moving ma- chine. This may happen at any moment in a shop where the machines are closely spaced, and where limited aisle-space is provided and piles of working material are allowed to remain on the floor. Any workman irt Fig. 1. A Badly Obstructed Shop. (Accumulation of material, such as liere shown, should be avoided, so far as possible. It it cannot be avoided, good illumination will materially assist the workmen in going about the shop without accident.) 30 THE TRAVELERS INSURANCE COMPANY going from one machine to another under such condi- tions must be extra vigilant to avoid colliding with other men or with materials they may be handling, and to avoid tripping over tools or material lying on the floor. Trucks. The men or boys who supply the machine operators with raw material, or remove the finished or partly-finished product, by means of trucks, are in danger of injury to themselves or of causing injury to others, in several ways. The truck will take up a large portion of the already limited space, and any person who wishes to use the passage is at a disadvantage. The man loading the truck is likely to have his hand or clothing caught in neighboring machinery, or he may accidentally move a belt-shifting rod or other machine- starting device. Any one of these actions is likely to cause an accident. In pushing trucks about the shop it is often neces- sary for them to pass one another, and there is seldom any special place or space reserved for this purpose. The men in charge of the trucks usually take advantage of the first handy nook or recess, and try to get by one another. In doing this their hands sometimes become bruised, lacerated, or crushed. If the men try to pass in the narrow aisle the trucks are likely to collide, thus knocking off some casting or other object that may have been insecurely placed. In the event of an injury from any of these causes, the crowded condition of the shop is not held accountable for it, as a rule, — some other proximate cause being assigned. This is in accordance with the general principle that a thing or a person often bears blame that should rightfully be placed upon a condition. THE SPACING OF MACHINES 31 Systematic Spacing and the Use of "Dead Lines." The old-fashioned method of placing machines in a shop does not make for efficiency or for safety. For- merly the manager or owner would go into his factory and say, "We will place one machine here, and another one there," — the location being indicated in each case by the space measured between the extended arms. Very likely the machines would fit in the spaces allotted, but it does not follow that the operations at the ma- chines could be carried on there properly. The modern manufacturer who is seeking safety and efficiency will ascertain, beforehand, the dimensions of the machine he is to install, and he will also find out how much space should be allowed for the worker, and Fig. 2. Showing a Good Central Aisle with Conspicuous "Dead-lines." 32 THE TRAVELERS INSURANCE COMPANY how much area his operations will cover. He will likewise ascertain the probable rate of production, and the rate at which the material can be supplied and the product passed on to other departments. With this information at hand it is easy to lay out the factory and locate the machines, so that efficiency, orderliness, and safety will all be assured. It is an excellent plan to have so-called "dead lines" painted conspicuously on the floor to mark the limits of the aisles. Lines of this kind should be re-painted whenever they tend to become indistinct, and fore- men should see that nothing is allowed to extend over them. Fig. 2 illustrates the idea of the "dead line" very clearly. The advantages of wide, clearly-defined aisles of this kind are numerous. They promote effi- ciency as well as safety, and as the men will use them in preference to the tortuous and narrow passages between stock piles and parts that may be lying upon the floor, the foremen are better able to note how much the men walk about, and this may lead to improved methods of handling the work. IV. SHAFTING AND BELTING. Importance of Proper Safeguarding. The proper safeguarding of the apparatus used for power trans- mission is exceedingly important in machine shops, as well as in shops of every other kind, where power is needed. In a large shop that does not have individual electric motors for its various machines, a great many belts are used, and rope and chain drives are also em- ployed occasionally. The accidents that occur in connection with equipment of this kind may be divided into two principal groups — the first comprising those due to the breaking of the belts, ropes, and chains, and the second, which is more important, including those in which the hands or clothing of workmen are caught in the moving transmission apparatus. Wear and deterioration of belts may be caused in various ways. Frictional heat injures leather belts by burning the fibers, and this action is particularly rapid when the belts slip excessively. Belts hanging loose on revolving shafts, and even belts in operation, may be rapidly worn away by abrasion when the air of the shop contains gritty dust. Temperature, moisture, the tightness or looseness of the belts, and the general condition of the lacings and fastenings, all have an influence upon the life of the belts, and also upon their efficiency in transmitting power. Driving chains wear chiefly by the friction between the links and the sprockets. 34 THE TRAVELERS INSURANCE COMPANY Fig. 3. An Unguarded Horizontal Belt, with Workmen Directly Beneath It. SHAFTING AND BELTING 35 In case of deterioration from any of these causes, it is only a question of time when breakage must occur, and then the results are likely to be serious. When a belt breaks the adhesion between it and the driving pulley sometimes holds the belt long enough for it to roll up, after which it is shot off at a speed comparable with the speed of the pulleys over which it runs. At short range a roll of this kind may be as deadly as a cannon ball, and it takes no very active imagination to picture the result, when it is discharged into the midst of a busy shop. A broken belt may also start to roll up, get caught, and then pull down a section of the line shafting. The only method of preventing these accidents is to provide suitable guards for the belts so that even if they break they will not be thrown off. Frequent inspection to remove dirt and grit, and to find weak places, is also of great value. If the belts are seriously worn, the expense of replacing them should not be spared, because the increased efficiency and safety attending such replacement will be ample compensation. The second general kind of accident caused by transmission apparatus is that in which a workman is caught in a moving belt by his clothes or hands, and thrown to the floor or whirled about the shafting. This is one of the most fearful of all industrial accidents, resulting in serious mutilation in almost every case, and we could easily fill pages with the awful details of accidents of this kind that have come to our know- ledge. The only way to eliminate such hazards is by thoroughly and completely guarding all power-trans- mission equipment where there is the slightest proba- bility of a workman getting caught. 36 THE TRAVELERS INSURANCE COMPANY u o N o X o Q « o § o SHAFTING AND BELTING 37 Fig. 5. A Metal Guard for a Horizontal Belt. (It is far better to join the side-bars of such a guard by lattice-worlc, instead of by rungs as here shown.) 38 THE TRAVELERS INSURANCE COMPANY Fig. 6. A Guard for a Vertical Belt. SHAFTING AND BELTING 39 Relation of the Safeguards to the Lay-out of the Shop. A general point that should be considered in the installation of belt guards is the arrangement of the power- transmission apparatus. This is most important, of course, when a complete installation of new machin- ery is about to be made ; for in cases of this kind it is far easier to safeguard the belting properly, if the shop is laid out with due attention to the need for the guards. When no preliminary thought is given to the subject of safeguarding, the chances are that no guards will be installed, or else the work will have to be done subse- quently at a much greater cost, and will cause more or Fig. 7. PIrotection for a Low Belt and Pulley. '40 THE TRAVELERS INSURANCE COMPANY less temporary or even permanent inconvenience. Moreover, human nature is constituted so that when it is inconvenient to do a certain piece of work, a reason can usually be found for delaying or entirely neglecting it ; and when it is the guarding of transmission apparatus that is under consideration, this reason will often be considered to hold good until an accident occurs. A preliminary study of the problem, at the time the shop is laid out, makes it possible to have the guards installed so that they will not obstruct the aisles or passageways, nor interfere with the working, repair, or inspection of the machines. It may also be decided, in this general plan, whether open methods of guarding by means of rails or angle iron are to be used in certain locations, or whether it is better to entirely inclose the apparatus. Standards for Belt Guards. All vertical and in- clined belts (and chain and rope drives also) should be effectively guarded in accordance with one of the follow- ing methods. If the guard is placed within 4 inches of the belt it should be at least 6 feet high, and should be of solid or wire-mesh construction, with openings not greater than half an inch each way. When the guards are placed from 4 to 15 inches from the belts, the open- ings in the mesh may be larger, but they should not be more than two inches each way. In either case the wire (if wire-mesh is used) should not be smaller than No. 20 gage. If the distance is 15 inches or more, guard rails may be used, provided they are of substantial con- struction, not less than 42 inches high, and have an additional rail midway between the top rail and the floor. When the belt passes through a floor a six- inch toe-board should be installed about the floor opening. SHAFTING AND BELTING 41 Fig. 8. Well-arranged Belt Guards for an Upright Drill. (A cone belt-shifter should be provided. If a guard of this kind is within 4 inches of a belt or pulley the openings in the wire mesh should not exceed half an inch in their greatest dimension.) 42 THE TRAVELERS INSURANCE COMPANY Fig. 9, Guards for a Sensitive Drill. (The wire mesh, in this case, is four inches or more from the nearest belt or pulley. Similar guards, when placed closer than four inches, should be made of half-inch mesh. In the guard here shown, the netting should be extended so as to inclose the belt and pulleys as completely as practicable, at the front and bottom. The pro- jecting handle for shifting the belt should work in a slot, which should be no wider than is essential to the proper opera- tion of the shifter.) SHAFTING AND BELTING 43 Fig. 10. A Machine-drive Belt-guard of Good Type. (Note the method of adjustment, indicated by the arrow, to suit the angle of the drive.) 44 THE TRAVELERS INSURANCE COMPANY The specifications for horizontal-belt guards are similar to the foregoing. In case a horizontal belt runs in a pit, six-inch toe-boards should be installed on all exposed sides of the pit. Horizontal belts that are not more than 7 feet above a floor or a working platform should be guarded on the sides and underneath by solid or wire-mesh troughs. It is of course logical to take the speed and width of belts into account in estimating their hazards. AH overhead belts, six inches or more wide, that run at a speed of 1,800 feet or more per minute, should be guarded with special care. The wire-mesh guard framed with angle iron, or the ladder guard turned over at each end so as to include the pulleys, is recommended. In the case of the ladder guards the rungs (if rungs are used) should be close enough together to prevent the belt from fallirtg to the floor in case a break occurs. It is far better, however, to use lattice work instead of rungs, between the side-bars of the guard. All belt guards should be securely fastened in place, and should be of such size and arrangement that a hand or any other part of the body cannot project through, over, around, or underneath them, so that it can be caught at the point of contact between a belt and a pulley, or between the spokes of a pulley, or between a pulley and any adjacent framework or other fixed object. Shifting Belts. In view of the high speed often attained by belts, it is evidently important to make some adequate provision for shifting them with safety. Approved mechanical belt-shifters should be provided in each case, in connection with tight-and-loose pulleys; and it is advisable to have these shifters equipped SHAFTING AND BELTING 45 with rollers where they come in contact with the belts. This not only reduces the wear on the edges of the belts (and this may be considerable in the course of a year), but also minimizes the chance of the edge of a belt catching in the belt-shifter and causing damage. The belt-shifter should be provided with an approved automatic locking device, and the handle of the belt- shifter should be located so that the workman can operate it from his regular working position without inconvenience. A belt that has been thrown off from a pulley is often allowed to ride on the revolving shaft. This is very dangerous practice. Such a belt, especially when loosely joined by lacing, may gradually travel around until the joint reaches the shaft, and then be drawn tight enough to engage the driven pulley, and thus suddenly start the machine. This is particularly true of small pulleys, and though this specific danger may appear to be remote, we could cite cases in which it has led to serious consequences. Belts that have been removed from pulleys and allowed to hang from revolv- ing shafting sometimes catch on set-screws, bolt-heads, and other projections on pulleys or on the shafting itself, and wind up in such a way as to entangle persons near by, and injure them seriously; and sections of line shafting, as well as countershafts, are sometimes pulled down by belts that have been left hanging in this way, and have become caught on fixed objects. Install belt hooks or perches near all pulleys from which the belts are likely to be removed, and never permit the belts to hang from revolving shafting. Although we strongly advocate the installation of mechanical belt-shifters or approved clutches, we are 46 THE TRAVELERS INSURANCE COMPANY Courtesy of the Eastman Kodak Company. Fig. 11. Guarded and Unguarded Drive Clutches. (The one in the foreground is unguarded. The two in the background are guarded.) well aware that in many plants the shifting is still done by hand, or by the use of poles. Hand-shifting is too dangerous to be tolerated, and the use of a pole or stick adds but little to the safety of the operation. A single accident may be cited as an illustration of the danger. While an employee was shipping a belt by means of a stick, the stick slipped between the arms of a moving pulley and was forced back into the workman's side. Two of his ribs were broken, and internal injuries also resulted. This accident could not have occurred if tight-and-loose pulleys and a suitable mechanical belt- shifter had been installed previously. An even more dangerous procedure is that of removing or shifting belts with the feet. SHAFTING AND BELTING 47 Dressing Belts. The operation of applying dress- ing to belts to prevent them from slipping leads to many serious accidents. Care should be taken to apply the dressing at the point where the belt leaves the pulley, and to roll up the sleeves so that they will not catch upon belt fastenings or other parts of the belt. It is scarcely feasible to dress a belt satisfactorily while it is stationary and in position on the pulleys, because it is then very hard to reach all parts of the belt, and to apply dressing smoothly and uniformly. The safest and best way, without doubt, is to remove the belt altogether, when it needs dressing, and stretch it out along a bench or on a clean floor. It should then be thoroughly cleaned and curried, after which the new dressing may be applied and worked in. There are few shops, however, in which the superintendents are willing to have the work done in this way, not only on account of the cost of the labor, but also because it would often be necessary to have extra belts on hand, to take the places of those that were being cleaned and dressed. Yet although it would seldom be feasible to remove large, heavy belts as here described, small ones can be handled in this way without prohibitive cost, and it is often possible to do the work outside of the regular hours, so that it will not be necessary to provide extra belts. If a belt must be dressed while it is running, the work should be assigned to a man who is known to be intelligent and cautious, because in such cases the prob- lem of accident prevention is probably more than 75 per cent, a human problem. In other words, it will depend mainly upon the man himself, whether he is injured or not. Liquid dressing should first be warmed so that it 48 THE TRAVELERS INSURANCE COMPANY will flow freely, and it should then be applied by a brush and never by the use of rags or cotton waste, because either of these is likely to catch on belt fastenings or rough places at the edges of the belt, and the man may be caugfit also, and. be badly hurt. Experts often re- commend that the engine (or motor) driving the belt be slowed down while the dressing is applied. This is an exceedingly wise precaution, where it can be done satisfactorily. In dressing a moving belt the dressing, as previous- ly stated, should be applied to the belt near the point where the belt leaves the pulley. Sometimes, however, this is not practicable on account of local conditions, and in such cases extraordinary care should be taken. We recall one plant, for example, in which a belt two feet wide, running over a six-foot pulley, had to be dressed when no part of it was accessible except a sec- tion within two feet of the pulley, on the in-running side. Moreover, the belt could be approached only from one side, so that the man who applied the dressing had to reach over to the further edge of the belt from where he stood. To guard against accident he was in the habit of removing his jumper, turning back his right shirt-sleeve into a tight roll as near as possible to his shoulder, and working with his right arm bare. Conditions of this kind should be corrected if possible; but if no change for the better is practicable, a stout railing should be provided for the protection of the man, and it should be placed so that he can lean upon it if necessary, and so that he can catch at it and thus save himself, in case he should lose his balance. When a man is engaged in any perilous operation, of this kind or any other SHAFTING AND BELTING 49 kind, care should be taken to prevent his being startled by any unusual sound or other disturbing cause. Nobody wearing ragged or loose-fitting clothing should be allowed near a rapidly-moving belt, either to apply dressing to it or for any other purpose. Many persons, to save a little time or inconven- ience, are willing to take the chance of being injured, by passing through moving belts or by stepping over or across them. This should never be done, unless a safe and thoroughly-protected passageway is provided. Chain Drives. When chains are used for the trans- mission of power, they should be guarded with special care. The hazard of this kind of a drive is about the same as that of gearing. Most chains are installed in a horizontal or nearly horizontal position, and so that both sprockets are within reach of the workman. He is then in danger of having his hands or clothing caught between the chain and the sprockets. It is essential, for proper safeguarding, to inclose the chains and the sprockets completely. Fall of Shafting. Another hazard that must be considered in shops is that due to the fall of overhead shafting. Accidents of this kind are somewhat unusual, because the danger is so obvious that even the most careless managers usually take precautions against it; but when a section of shafting weighing tons and run- ning the length of the building does fall, enormous damage is likely to be caused. A space somewhat greater than the width of the belt should be left between every pulley and the one nearest to it on the same shaft (except in the case of tight-and-loose pulleys that are operated together), and also between every pulley and the nearest hanger, so that the belt so THE TRAVELERS INSURANCE COMPANY cannot get wedged and pull the line shafting down. If it is not possible to arrange the pulleys in this way, the spaces should be effectively guarded, so that the belts cannot get into them. Too much care cannot be exercised in making sure that the supports for line shafting are substantial, and that they are securely fastened. A weak or insecure hanger imposes an extra burden on the other hangers, and the shaft is ultimately thrown out of alinement. It then moves with an eccentric motion, which gradually becomes more pro- nounced as the other hangers are affected by it and work loose. The belt becomes tight during one part of each revolution of the shaft and slack during the remaining part, and by and by a heavy load is applied at a moment when the belt is abnormally tight, and the whole line of shafting comes down, with disastrous results. Of course this does not always happen, yet it does happen every once in a while, and the only certain way to prevent it is to keep the shafting and the hangers in good condition at all times. Splicing Belts. Inspect all belts thoroughly and frequently, giving special attention to the joints or splices. See, also, that all ragged ends of belts and loose ends of lacings are neatly trimmed off. A wide difference of opinion exists as to the best method to be used for joining the ends of belts for power transmission, and there are probably few operations in a factory or shop that give rise to so much discussion and argument as this apparently simple one. There are hundreds of thousands of belts in operation every working day of the year, varying greatly in width and length, and operated at different speeds and under conditions of all kinds. The care and repair work SHAFTING AND BELTING SI necessary to keep this vast amount of auxiliary power- transmission apparatus at top efficiency is an important element in factory economy and much has been written about it. In this section we shall limit our remarks to the joining of the ends of belts, with particular reference to the safety features. Belts may be joined by cementing, riveting, sew- ing, or lacing, or by using hooks or clips ; and sometimes a combination of these methods is used. Each process has its advocates, who differ among themselves as to the best method for doing the work, A group of millwrights or machinists may perchance agree that lacing is the most practical method of joining belts, but they are quite likely to differ as to whether rawhide or wire is preferable, and they might also disagree with regard to the proper spacing of the holes, and the manner of running the lacing. In making belts, the ends of the finished strips of leather are scarfed down, covered with cement or animal glue, and firmly pressed together until they adhere strongly. Some belt-users stipulate in their orders that in addition to the cement, the end of each strip shall be either riveted or sewed to the end of the adjoining strip. This is not usually done, however, because belt manufacturers consider it to be unneces- sary, and the thousands of belts that are made up with cement only, and which are in use to-day after long periods of service, give ample proof of the security of a well made cemented joint. By joining the ends of the finished belt in the same way, a smooth finish is obtained and ample strength is also provided. The essential thing about joining belts by any method whatever, is to see that the work is properly 52 THE TRAVELERS INSURANCE COMPANY Fig. 12. Showing the Proper Position of the Cemented Joint. (The belt thickness is exaggerated for greater clearness. The pulley on the left is more likely to slip than the one on the right, because it has a smaller arc of contact.) done; and this is particularly true of the cementing process. The job should be done by men thoroughly familiar with the work, because a belt, like the prover- bial chain, is no stronger than its weakest part, and if the joining is poorly done the belt, when put in service, is likely to give way and cause an accident. Even if a poorly-made joint does not fail immediately, it is almost sure to become loosened at the end of the scarf- ing, and to work apart gradually. When installing a belt with a cemented joint, see that the edge of the scarfing on the inner surface of the belt will be smoothed down, if the belt slips on the pulley where slip is most likely to occur. (This point is illustrated in Fig. 12.) If the belt is put on the other way, slipping may start the scarfed end of the lap, and cause it to gradually roll up. After action of this kind has become well developed, severe stresses are likely to be produced in the belt every time the affected SHAFTING AND BELTING S3 section passes over a pulley, and these often strain the belt until it gives out. There is danger of an accident when this happens, and workmen are also likely to be caught by the loosened joint, even while the belt is still in service. The time required for joining belts by cementing the ends is one of the chief objections to this method, and on account of it many belt users prefer to lace the ends of the belts together, either with rawhide or with wire. It is certain that a strong, serviceable joint can be made by either rawhide or wire lacing in much less time than is required for a cement joint, and the advent of machines for wire lacing, and for joining belts with wire clips, has further reduced the time, so that the entire operation may be carried out in a few minutes. Accidents happen, however, when this method of join- ing is used. The end of a rawhide lacing sometimes works loose and wraps itself around some part of the person or clothing of a man standing or passing near the belt, with serious consequences. Similarly, wire lacing often works loose, and even a very small part of it, protruding beyond the edge or outer surface of the belt, may inflict severe injuries upon employees who happen to come in contact with it. In fact, a fastening device of any kind, when slightly loosened, becomes a fast-traveling accident-producing agent. The dangerous practice of lacing belts without first stopping the machinery also causes many accidents, and it should never be countenanced. An Accident Involving Belt Clips. A somewhat peculiar and instructive accident came to our notice some time ago in connection with an electric motor that is installed near the ceiling of a factory and connected 54 THE TRAVELERS INSURANCE COMPANY Fig. 13. Window Panes Pierced by Flying Belt Clips. SHAFTING AND BELTING 55 by a belt to a line shaft The belt, which was joined by means of metal clips, failed at the joint, and the clips were expelled with such force that several of them passed entirely through the glass in a window 25 feet distant. Fortunately no personal injuries were in- flicted, but it is easy to imagine the serious consequences that would have resulted if one of the flying clips had struck an employee in the eye. Overloading Belts. Overloading belts frequently causes them to fail at the joints. The safe working load may be learned from the manufacturer of the belt, and this load should never be exceeded. It is seldom, however, that the tension is estimated with any degree of care when a belt is being tightened. The usual procedure is to decide how much to cut out, after which the ends are pulled together and joined by one of the methods already mentioned. The tension on the belt is then arrived at by pure guess-work, and it may or may not exceed the safe limit. If the tightening is done during damp or rainy weather, excessive strain on the belts and shafting is almost sure to be produced, as the belts dry out. Broken belts, bent or broken shafts, and burned-out journals and bearings may then be expected, with many consequent opportunities for accidents. The belts should be examined periodically, and a belt-tension scale reading taken. In this way the owner can determine whether or not the belts need tightening, and at the same time he can find out just how much should be cut out, if it is found necessary to shorten them. When a belt is put on a pulley or removed from one (except as it is shifted on or off from an idle pulley) it engages the rim at an angle that produces an excessive 5B THE TRAVELERS INSURANCE COMPANY bending moment. If it is the joined section of the belt that engages the pulley, and this operation is repeated a number of times, the rough treatment will tend to loosen the joint, whether it is made with rivets, wire clips, metal clamps, cement, or lacing. Trouble from this source may be avoided by the exercise of care, and it should be remembered that no belt joint will remain safe if subjected to indiscriminate abuse. Oiling Shafting. Numerous accidents occur to men whose duty it is to oil the bearings of overhead shafting. It is highly desirable to avoid the oiling of shafting while it is in motion, but this is not always practicable, when the bearings are of the usual type. A special form of bearing, known as a "ring bearing," is favored by many shops, and it is to be commended to the attention of those who have not tried it, inas- much as it greatly lessens the likelihood of accidents from oiling. This form automatically supplies oil to the bearing from a small reservoir which holds a suf- ficient amount to last for a week or more. The reser- voirs throughout the shop can then be filled on Sunday, while the machinery is idle, and in this way the danger from oiling moving shafting is entirely obviated. When the bearings are of the ordinary type, they can be oiled with a fair degree of safety by doing the work from elevated platforms or walks, properly railed, and running parallel with the shafting for its entire length. Provision can often be made for platforms of this kind when designing and laying out a shop, but it is usually a difficult matter to install them in a shop that was erected without reference to them. Another method that can sometimes be used with advantage con- sists in erecting, parallel to the shafting, an overhead SHAFTING AND BELTING 57 rail or track, along which an iron ladder travels by means of wheels or rollers. In most cases this plan is difficult of application in shops that are already in use, because the ladder would interfere with belts or pulleys, or with machinery on the floor. Vertical pipes, through which oil may be poured, are sometimes extended through the floor over the shafting and immediately above the bearings; but when this is done it is not easy to see how much oil reaches the bearing, and the attendant is therefore likely to use either too little oil, or else an excess of it. In the former case the bearing may run dry, while in the latter case a considerable quantity of the oil may be wasted. Special oil-cans are sometimes used, having necks or spouts bent in the form of a U at one end, — the necks being long enough to permit the oiler to lubricate the bearing while standing upon the floor. In some plants the man who is to oil the shafting comes early in the morning and does his work before the engine is started up. In some respects this is an excellent idea, but like every other method of doing work it has to be carried out in accordance with a def- inite and intelligent plan if accidents are to be avoided. The oiler should first report to the engineer that he is about to oil the shafting, and he should again report to him when he has completed his task; and the engineer should be instructed not to start the engine until he has received definite word from the oiler, in person, to the effect that the oiling is completed. The way in which accidents are likely to happen in connection with this program is fairly evident. The oiler, when he has finished his work, sometimes omits to inform the engineer that he is through, and the engineer, having 58 THE TRAVELERS INSURANCE COMPANY received no word when it comes time to start the engine, does not know what to do. If he does start the engine he may kill the oiler, while if he does not do so he may be delaying the day's work quite unnecessarily. In one case that we have in mind the engineer made a practice of looking over the plant under these circum- stances, to see where the oiler was; and he repeatedly found that he had gone away and forgotten to leave word. The engineer then returned to the engine room and started the machinery. After having done this a number of times he began to take it for granted that the oiler had merely forgotten to bring him the message, and thereafter he started up at the regular time with- out taking the trouble to look through the shop. It is evident that when the thing is managed in this way there is a strong probability that sooner or later the machinery will be set in motion while the oiler is in a dangerous position, and he will be likely to be killed or badly injured in consequence. Hence it is of para- mount importance, when this plan is adopted, to see that the oiler invariably passes the word to the engineer as soon as he is through with his work. Protection of Shafting. All dead ends of shafting which project more than two inches beyond a bearing or pulley hub should be cut off, or be guarded by a stationary sleeve, unless they are more than 6 feet above the floor. All horizontal shafting that is within six feet of the floor, or within six feet of a platform level, should be entirely incased. Vertical and inclined shafts should be solidly incased or be inclosed by wire mesh, to a height of 6 feet. The openings in the wire mesh should not exceed one-half of an inch. Safety couplings, collars, and set-screws should be SHAFTING AND BELTING 59 used in all cases. Take suitable precautions to pre- vent pulleys from working off at the ends of their shafts, and wherever it is practicable to do so, see that between every pulley and the nearest shaft bearing there is a clearance greater than the width of the belt. If this is not feasible, a screen guard should be located between the pulley and the shaft bearing. Keys. Another source of danger to workmen who are oiling or repairing shafting or pulleys is the project- ing key, which causes more trouble than many of the larger parts, though it often escapes notice on account of its small size. The danger is, that the key will catch a workman's clothing, cause the cloth to wind up about the shaft, and whirl the man around and seriously injure him. All projecting keys should therefore be effectively guarded. Moreover, this precaution should be taken, not only in places where the men are frequently required to work, but also throughout the entire plant; because the men, when called upon to do repair work in out-of-the-way or cramped quarters, are likely to forget that the dangers are not guarded there as well as in other places. It is hardly more dangerous to leave them all unprotected, than it is to give a false sense of security by attending to only a part of them. Periodic Inspections. A competent mechanic should be assigned to the work of inspecting the power- transmission equipment, and he should examine all parts of it carefully and at regular intervals. Such inspections are exceedingly valuable, because they often disclose dangerous conditions. It is impossible to consider all the problems of individual plants in a general discussion of this kind; 60 THE TRAVELERS INSURANCE COMPANY but if the various suggestions made in this section were adopted in every machine shop there would certainly be a noticeable reduction in accidents and a marked increase in general efficiency. V. INDIVIDUAL MOTOR DRIVE. Advantages of Individual Motor Drive. The ad- vantages, from an economical point of view, of driving machine tools of all kinds in shops, factories, and mills with individual electric motors have long been re- cognized. With individual drive there is a marked saving in power in consequence of the elimination of the transmission losses which always occur in long lines of shafting. The maintenance of pulleys, bearings, couplings, belts, and^other similar accessories that are essential in connection with shaft-driven machines is also avoided, and a considerable saving is made in lubricants, in time spent in shifting belts and in caring for bearings, and in numerous other ways. In addition to the economic phase of this ques- tion, there is another matter to be considered which is even more important, — namely, the safety of the workmen. The advantage is here also with the in- dividual drive, for it not only saves money but also is. an important feature in reducing accidents. Shaft-driven machines are ordinarily started by means of a treadle or a lever, which shifts a belt or operates a clutch. On machines like punches, presses, and shears, accidents often happen by these treadlea or levers being touched unintentionally, thus starting the machine and seriously injuring a workman en- gaged in setting dies or adjusting shear blades. With individual motor drive the starting switch can easil>^ 62 THE TRAVELERS INSURANCE COMPANY be placed out of the way, so that the accidental start- ing of a machine would hardly be possible; and all accidents of the nature here referred to could be elim- inated if shaft-driven machines were abolished. The accompanying illustrations, showing machines equipped with individual motor drive and shops equipped with shaft-driven machines, clearly demon- strate the advantages of the more modern arrangement, from the standpoint of accident prevention. Shafting is usually located along the ceiling, and the bearings and other accessories can then be reached only by ladders, or from elevated platforms specially constructed for this purpose. The bearings and pulleys require more or less attention, and the men who have to take care of them, often working on the ladders in crowded and cramped positions, are frequently ex- posed to danger. Moreover, repair work upon and about the shafting must necessarily be done from scaffolding, and this is often more or less insecure, so that the millwrights are likely to be injured by working upon it. Shafting, pulleys, and belts make it difificult or dangerous to handle material by cranes or overhead runways, and accidents are likely to happen from such operations when using shaft-driving. With the ma- chines operated by individual motors, and the wiring run through conduits under the floors, there are no such obstructions, but the space above the machines and in the passageways between them is free, so that material can be handled from overhead easily and with much greater safety. Belting, shafts, bearing hangers, and the other appliances pertaining to shaft- driving, cut off a INDIVIDUAL MOTOR DRIVE 63 considerable amount of light around the machines, and often make it necessary to use artificial illumination all through the day; whereas with individual motor drive these obstructions are avoided, so that the light in a room that is equipped with individually driven machines is usually much better than that in rooms with shaft-driven machinery. The belts not only intercept the direct light from the windows, but the ceiling is often darkened also, by dirt and oil thrown off by the belts and pulleys ; and as the hangers and pulleys are themselves dark, there is but little light reflected down upon the machines from above, and the gfeneral effect is often exceedingly gloomy. Fig. 14. Drilling MAcmNES Operated by Shafting and Belting. (The belts and other power-transmission apparatus should be guarded.) 64 THE TRAVELERS INSURANCE COMPANY With shaft-drive the machines must be arranged in parallel lines, usually ranging lengthwise of the building; and in order to economize floor space it is often necessary to place the machines back to back, so that half the men must work in their own shadows and the other half must face the light. Either of these conditions is trying to the eyes, and in the long run impairs the sight ; and it is also obvious that such condi- tions tend to materially reduce the output. When the machines must be placed in fixed positions in rela- tion to the shafting, and without regard to the direction of the light, and the operator consequently has to work in a dark place or with continuous artificial light, the likelihood of accidents is greatly increased. The contrast in these respects that is afforded by shops that are operated by individual motors is quite striking; for when individual motors are used the ma- chines can be located properly, with due reference to the best light and the safest arrangement as to floor space. Moreover, it is far easier to avoid undue crowding of the machines, — a matter that is considered in Sec- tion III, in connection with its bearing upon accidents. Electrical Accidents. The problem of preventing electrical accidents in the shop should be carefully considered, however, whenever a decision is made to adopt electricity for power purposes. Aside from those due to ignorance or gross carelessness on the part of the employees, nearly all electrical accidents in machine shops are due to lack of proper maintenance of the electrical equipment. The likelihood of acci- dents, and the amount of work involved in maintaining the apparatus in first-class condition, depend largely upon the judgment exercised in selecting the apparatus, INDIVIDUAL MOTOR DRIVE 65 and the care with which it is installed and used. This indicates that thoroughly skilled men should be em- ployed to supervise the work from the beginning. A competent electrician should be engaged to make all repairs, changes, and additions, no matter how trivial they may be; and he should also be charged with the duty of maintaining the entire electrical installation in first-class condition. Courtesy of the General Electric Company^ Fig. 15. A Motor-driven Bolt Cutter. (The motor casing is perforated to prevent overiieating of the motor. The gears, both large and small, are effectively guarded to prevent accidental contact with them.) 66 THE TRAVELERS INSURANCE COMPANY Courtesy of the General Electric Company. Fig. 16. A Large, Well-guarded Planer. CThe plates shown over the planer bed are very important and should always be provided. An inclosure (or the counterweights is shown at the right. The machine is driven by a direct-connected, reversible motor.) INDIVIDUAL MOTOR DRIVE 67 Grounding. All motor frames should be grounded, whether they are direct-connected to the machines or not; and all direct-connected machines should also be grounded if the pressure is over 200 volts. The latter precaution may appear to be needless, because thousands of persons have come in contact with electrical conductors carrying 200 volts or more, with- out receiving serious injury; but it must be remem- bered, on the other hand, that hundreds of persons have received severe shocks and burns, or have been killed, by contact with such conductors. A short circuit or other electrical disturbance is quite likely to charge the machine to which the motor is directly connected, and thus cause injury to the operator. Even if the electric current does not of itself injure the workman, it may nevertheless throw him against some other machine, or hold him at the charged machine until he is injured by the moving parts. Guarding Motors and Conductors. All the rota- ting parts of a motor, and all exposed live parts, should be inclosed by sheet-metal guards. Wire-mesh guards are not advisable in connection with motors driving metal-cutting machines, because chips from the tools are likely to fly through .the openings in the wire guard, short-circuiting the motor or damaging it in some other way. The sheet-metal guard, with no openings except such as are necessary for ventilation, not only prevents personal contact with live or rotating parts, but also protects the motor from chips and particles of grit. The conductors supplying the motors with power, and the cable connections, between the motors and the controlling apparaitus, should be laid in conduits up to points as close to the motors as practicable, and the 68 THE TRAVELERS INSURANCE COMPANY Courtesy of the General Electric Company. Fig. 17. A Well-arranged Bolt Head Grinder. (Note the inclosed motor, and the belt guards and grinding-wheel protection. A drum-type controller 13 shown at the left.) INDIVIDUAL MOTOR DRIVE 69 parts that extend from the conduits to the motors should be heavily insulated and securely guarded. All conductors should also be effectively protected from moisture. Switches and Controllers. The type and location of the controlling and prdtecting devices have a direct bearing upon the prevention of accidents from electrical motive-power apparatus. The electric drive has a marked advantage over other forms, owing to the fact that the control apparatus can be located at any point that is most convenient for the worker. Constant- speed motors of small size may be controlled by pendent switches just above the machines, or by push-button switches attached to the frames of the machines; and either type can be so located that a workman can reach Courtesy of the General Electric Company. h ^ *'' ' '"M ^^^^., ^^^SSBHIJIij^ ^pLi iqH^^V 'r Fig, 18. Horizontal Boring Mill with Individual Motor. (The belt, it will be noted, is surrounded by a stout metal guard, and is also inclosed at the sides with silbstantial' wire-mesh screens.) 70 THE TRAVELERS INSURANCE COMPANY it from his regular working position. Adjustable-speed motors, and large constant-speed motors, require con- trols having starting resistances. The drum-type controller is an excellent device for this purpose, because it can be mounted in almost any position that is con- venient for the workman. This type also permits of remote control (which is often a matter of convenience in large work) , for by the use of a splined shaft and miter gears the controller handle can be made to travel with the work or the tool, as the case may be, and thus always be within the reach of the worker. In the case of group drive the wiring can be so arranged that any one man at any of the several machines in the group can shut off the power by pressing a button switch. With properly-guarded machines and careful workmen the likelihood of an accident is small, but if the unex- pected should happen, the first cry of a man in peril will call the attention of his companions to his plight, and any one of them can instantly shut off the power. The immediate-relief action provided by the accessibility of this control, as compared with the time required for one of the men to go to a switch located near a distant motor, may be the determining factor as to whether the accident will be slight, serious, or fatal. Starting Panels. Another common device for the control of the motor is the starting panel with fuses or with circuit breakers. Numerous accidents, result- ing principally in burns, occur at the starting panel, and these are usually due to its defective condition or poor construction. The contact points of the rheostat sometimes become worn and burned to such an extent that the release fails to operate automatically when the power is shut off. This means that all resistance is cut INDIVIDUAL MOTOR DRIVE 71 out, and unless the workman observes the condition of the rheostat, or thoroughly understands its purpose, he is likely to close the switch at starting-up time, and receive severe burns from the resultant flash or arcing. Accidents of this kind simply emphasize the importance of skilled supervision in the selection and maintenance of the electrical apparatus. Open Knife Switches. We wish to direct special attention to the peril of the open knife switch. A list of the yearly accidents caused by this one device would fill pages of this book. The reason is, that the current-carrying parts are exposed, so that persons manipulating such switches are likely to come in con- tact with these parts directly, — or a piece of metal, while being handled by a workman, may accidentally touch them, — or a contact will be made in some other way, so that a burn or shock will result. This hazard can be entirely eliminated by the use of the inclosed safety switch, which, as the name indicates, is a controlling device with the current-carrying parts in- closed in a compartment and operated by a handle outside. It is thus impossible to come in contact with the charged conductors, and even if arcing or flashing should occur, the flame would be smothered or confined largely within the compartment. Fuses and Circuit Breakers. The fuse and the circuit breaker are commonly used as protective devices for the motors, their purpose being to guard against overloads. Circuit breakers are to be preferred be- cause, as a rule, they operate more quickly, and they can be replaced easily and without danger. Fuses do not ordinarily act as quickly as circuit breakers on overloads, and for that reason they are more likely to 72 THE TRAVELERS INSURANCE COMPANY allow the motor to become damaged. When a fuse does blow it is a common occurrence for a workman to replace it at once, instead of sending for the electrician. There is a two-fold risk in such a practice, — the first being the chance of the workman getting a shock from the fuse clips, and the second being the danger of a burn in case the fuse should blow again. The proper pro- cedure is to open the switch first of all, so there will be no danger of a shock or burn, and then to ascertain the reason for the blowing of the first fuse, and remedy the condition. The new fuse may then be inserted, and the motor re-started. ^ Wire-mesh or box guards about starting panels serve the purpose of protecting employees against accidental contact with live conductors, but dependence cannot be placed upon them for guarding against flashes. When a flash occurs it can easily come through the mesh, or through the aperture left for the switch handle or rheostat lever. The illustrations accompanying this chapter show various machine tools fitted up with individual motor drive in an approved manner. Incidentally, too, they show some good safeguards of various kinds, that are wholly independent of the electric drive, and are equally applicable (with minor modifications) to shaft-driven machinery. VI. THE SAFE OPERATION OF LATHES Tools. Many of the accidents that occur in con- nection with lathes are due to the displacement or breakage of the tool or of the piece that is being worked upon. When the tool is insecurely or improperly placed, it often works loose or causes trouble in other ways. Frequently it digs into the work, and then, unless the lathe is stopped immediately, the tool is likely to be broken or forced out of the tool-post, or the work may be thrown out of the chuck or the centers, or all of these things may happen at once, and in such an event the man operating the lathe may be severely injured. Select, a tool that is suited to the work in hand, make sure that it is in good condition in all re- spects, and see that it is properly set in the tool-post and firmly secured. Be sure, also, that the lathe spindle fits its bearings well, and that the carriage is not loose on the ways. Eye Protection. On certain kinds of work the eyes of lathe operators are endangered by flying chips of metal. Provide goggles for the operators, and see that they are worn whenever dangerous work is being done. Guards of stout wire-mesh, framed, and secured to the tool-rests so that they will intercept flying chips, have been used to a considerable extent, and a guard of this kind is shown in Fig. 19. Far better protection is afforded by the use of heavy plate glass (instead of wire-netting), as illustrated in Fig. 20, and we strongly recommend the glass. ;Care should be 74 THE TRAVELERS INSURANCE COMPANY taken, however, to keep it clean, so that the work can be seen distinctly at all times ; and the guard should be made so that it can easily be adjusted or removed. To prevent splintering in case of breakage, the window may be made of two pieces of glass, cemented together with a thin film of transparent celluloid between. Chips that lodge in the ,eyes cause severe pain, and the injuries they produce are often extremely Fig. 19. A Wire-mesh Eye-protector Guard. THE SAFE OPERATION OF LATHES 75 serious. Unskilled treatment of such injuries adds greatly to the danger, and a physician should therefore be consulted at the earliest practicable moment, in case of any accident of this nature. Filing. Filing, if improperly done, is a hazardous operation. Every machinist knows that he is taking chances when using a file without a handle, yet many of them do it. The foreman or superintendent of the shop should make it his personal business to see that this practice is discontinued. The position in which Courtesy of the General Electric Company^ Fig. 20. A Plate-glass Eye-shield as Applied TO a Tool-post. (This is far superior to the wire-screen guard shown in Fig. 19.) 76 THE TRAVELERS INSURANCE COMPANY the file is held is also of great importance, because even when the handle is in place the file may be pushed* back against the operator's jabdomen with great violence. Always hold the file in such a way that in case it is forced back, the handle will be pushed to the side of the body instead of directly against it. Filing irregu- larly-shaped pieces, with projecting portions, must be carefully done, and the operator should keep his at- tention closely confined to the Work. Rolling up the sleeves is important, so that they will not catch on pro- jections on the work or on the face plate. When lean- ing over to inspect the work always keep in mind the danger of being struck by some portion of it. Set-screws and Other Projections, The older types of lathe dogs with projecting set-screws are Fig. 21. A Pipe-guard for Confining Long Rods Projecting Beyond the Headstock. (The rod or bar is inside the pipe, and the pipe is supported by forlced standards, as shown.) THE SAFE OPERATION OF LATHES 77 very prolific in accidents. These are being replaced in large measure by dogs in which safety or guarded set-screws are used, or by other types having no pro- jecting parts. So far as practicable, all face-plates and chucks should present smooth, even surfaces with no set- screws or other projections upon them. When ad- justing a chuck be sure to remove the chuck wrench before starting the lathe. Pins, bolts, and other similar objects are often ma- chined from solid bars which, at the beginning of the operation, may project several feet beyond the head- stock of the lathe. These bars frequently revolve at considerable speed and constitute a source of danger similar to that of unguarded shafting. Provide suitable tubes to cover all such bars, or rail off the spaces over which they extend. Belts. Give careful attention to the driving belts, pulleys, and shafting for lathes. Practically all lathes are provided with cone pulleys for varying the speed, and the belts often have to be changed from one step of the pulley to another. Mechanical belt-shifters appHcable to cone pulleys may be had, which will do this work satisfactorily; but they have not been ex- tensively adopted. Lathe operators often grasp the belt while the power is off, to turn the lathe to the proper position for making necessary adjustments. For this reason it is advisable to join these belts by cemented splices, rather than by the use of metal clips or wire lacings, to avoidinjiiTies to the hands. The handle of the belt- shifter, or other device for shutting off the power from the lathe, should be located in a position where it is 78 THE TRAVELERS INSURANCE COMPANY THE SAFE OPERATION OF LATHES 79 conveniently and quickly accessible, so that there may be no delay in stopping the machine in case of emergency. In many modern shops the individual motor drive has been applied to lathes, in some cases the motors being geared directly to the machines, while in other cases the power is transmitted by means of short belts. This method is admirable from a safety stand- point, and manufacturers should give it due consider- ation when contemplating extensive changes or new installations. Gears. Provide adequate and effective guards for all gears, and see that they are kept in position while the lathes are running. If it is necessary to remove them for any reason, make sure that they are replaced before starting the machines. It is exceedingly dangerous to clean, oil, repair, or adjust machines while they are in motion, and rules should be adopted and enforced prohibiting practices of this kind. Avoid reaching over the lathe to change the back gears before the machine has come to a dead stop, as otherwise some part of the clothing may be caught and drawn into the machine, causing serious injuries. The lathe itself is also likely to be damaged if the gears are changed while in motion. Miscellaneous Suggestions. Use a brush when removing filings and chips from a lathe, because severe cuts are often received when doing this work with the bare hands. Avoid changing clothes while standing near moving belts or machinery of any kind, and do not wear torn or ragged clothes or unbuttoned or loose jumpers. Machinists should also remove rings from their fingers before starting work. 80 THE TRAVELERS INSURANCE COMPANY Do not leave tools lying about on the machines or on other elevated places from which they may be jarred or pushed off, but place them in a tool box or rack provided for the purpose. Many other causes of accidents to operators of lathes might be mentioned, but the ones suggested above are responsible for most of the injuries that occur, and if the recommendations that are made in this section are faithfully observed, the safety and the efficiency of the men will be greatly increased. Vn. FORGING AND HAMMERING. Early Forging. Most of us have seen pictures illustrating the efforts of primeval man to fashion a weapon or a domestic utensil from metal. A large stone took the place of the modern anvil and a smaller stone served as a hammer. These, with a near-by wood fire, constituted the equipment of the earliest recorded forge shops. The equipment of the forge shop of the present day differs only in the more per- fect adaptation of the tools for the work in hand, and in the method of heating the metals. The principle of working the metals, — namely, by pressure, either intermittent as in hammer blows or constant as in hydraulic presses, — is the same. Burns and Sparks. Although there are no records, it is fair to assume that primeval man was subject to what he might have considered annoyances in the form of burns and bruises. These same hazards are present in the forge shop of to-day and are accepted by the smiths as necessary evils. A piece of iron or steel may be hot enough to cause a painful burn and still have the appearance of cold metal, and burns caused by the smiths mistaking these hot pieces of metal for cold ones are common. It is often a little incon- venient to get a pair of tongs before attempting to handle a piece of metal on the shop floor, but it is much safer to do so. 82 THE TRAVELERS INSURANCE COMPANY Another danger to which forge-shop men are sub- ject is that of sparks flying from hot metal. When a smith takes a bar of iron or steel from the fire he almost always gives it a light tap on the anvil to knock off the oxide. Even with this precaution the first few blows of the hammer or sledge are likely to produce showers of sparks, and a large spark of this kind, lodging in loose or ragged clothing, may burn the skin or even set fire to the clothing. This danger is so well recog- nized that, as a rule, smiths wear leather aprons which protect the body from the chest down. One of the inconsistencies in the forge shop lies in the fact that protection is thus given to regions where burns will heal in a short time if they receive proper care, while similar precautions are rarely taken to guard the eyes, which are far more vulnerable. A single spark may be sufficient to destroy the sight of an eye, and yet the smith will seldom wear eye protectors. Tools. Another point in the forge-shop equip- ment that requires careful attention, but is often neg- lected, is the condition of the tools. Swages, flatters, fullers, breaking-down tools, and tools of various other kinds that are frequently subjected to sledge-hammer blows, often have their heads reduced to a burred con- dition. Sooner or later some of these jagged, burred projections will fly off under the hammer, and it is then purely a matter of chance whether or not some one is injured. Better work can be done with a good tool than with a poor one, and economy as well as safety is increased by repairing or discarding tools with burred heads. Power Hammers. The advent of drop or stamped forgings has had an important influence on the iron FORGING AND HAMMERING 83 and steel industry. Forgings of this kind can be turned out far more quickly than castings, and they are often much cheaper also. The uniformity in di- mensions and accuracy in shape that are characteristic of such forgings likewise adapt them very well for economical machining or finishing. Two types of hammers are in general use for stamped forgings, — namely, the board drop-hammer Fig. 23. Miscellaneous Tools in Poor Condition. and the steam hammer. The board drop type is commonly used for small forgings, while the best re- sults for large pieces are obtained by using the steam hammer. Larger forgings, plate work, and work in which bending operations are prominent, are best produced by hydraulic presses. When drop-hammers were first introduced, it was thought necessary to provide foundations having a 84 THE TRAVELERS INSURANCE COMPANY certain amount of resiliency in order to start the hammer on its return, and at the same time remove the scale by vibration ; but foundations of solid concrete are now being used with much better results than were at- tained by the older type. Tar paper, or boards one or two inches thick, should be placed between the base plate and the concrete, to prevent excessive wear or grinding at the top of the foundation. It is asserted that a drop of the hammer on a foundation of this kind brings about better results than a drop one-third longer on the old type. This means a saving in time and power, and in some cases may do away with the neces- sity of a second heat. The modern drop-forge shop is equipped with a suction system by means of which the scale is removed from the dies. What has been said above regarding the impor- tance of protection to smiths from flying sparks applies with equal force to drop-hammer operators. In each case hot metal is worked, and although dies are used in connection with drop-hammers, so that the scale can- not escape as readily as it does from the smooth sur- face of the smith's hammer, the drop-hammer delivers far heavier blows, and the sparks that it produces are forced out at a much higher speed, and even the smallest of them gives rise to a distinctly hot, stinging sensation upon striking the body. The operation of many of the single-frame steam hammers in use to-day is fraught with hazardous possibilities. The steam throttle lever is often so located that the operator's view of the work is obstruct- ed by one of his arms, while with the other he adjusts the controlling lever. To avoid this he must stoop over in an exceedingly awkward position, and even then his FORGING AND HAMMERING 85 view of the work may be obscured. When a battery of these hammers is in operation, the noise is so great that it is almost impossible to give oral instructions or orders to the men at the hammers, and signs must be used instead. A mistake in giving or interpreting the signs, or failure to see them, coupled with the difficulty that the operator has in seeing the condition of the work, may easily lead to accidents. The danger from this source has been largely eliminated in the newer designs of steam hammers wherein the controlling lever and the throttle lever are placed on one stud, a rod forming the connection between the throttle lever and the steam valve. The operator can then control both levers with his hands below his head, and he is thus enabled to see the progress of the work and correctly interpret the signs of his fellow employees. Pressing and Trimming Operations. Cold-press work and the trimming of forgings cause many dis- tressing accidents unless proper precautions are taken to guard against them. The accidents from this cause are in the same class as those from punch presses. There is a fatiguing monotony connected with the work of placing forgings in the trimming dies, and therefore the operator who does this work by hand is likely to become momentarily careless, so that once in a while a forging is not properly placed in the die. In most cases it seems impossible to overcome the desire to correct the error, even though the lever has been tripped to let the hammer fall. Under such circumstances a serious accident is almost sure to occur. This danger is so well recognized in some shops that special tools are provided, or effective safeguards are installed, or both precautions are taken. 86 THE TRAVELERS INSURANCE COMPANY Cyanide. In many shops in which forging or hammering is done, cyanide is used to a greater or lesser extent, for case-hardening. It should always be remembered that this substance is one of the deadliest poisons known, and special care should be taken to avoid taking any of it into the mouth, or inhal- ing any of the fumes that arise from it. Cyanide should be kept in a safe place and be plainly marked Poison, and it should not be allowed to become scattered about upon the floor, forge, anvil, or workbench. Draft hoods should also be provided for removing the fumes that are produced when working with cyanide, and nobody should be allowed to handle it unless he has been fully instructed with regard to the danger involved. This warning is specially important, because the men who use cyanide often do not know its deadly character, and it is hard to understand why more fatalities do not result from it, except upon the theory that there is a special good angel that looks after blacksmiths and others engaged in similar work, to keep them from this particular form of harm. We have seen men who should have known better (but did not), thrust pieces of hot metal into cyanide, and stand over the work with the fumes rising up all around, while they were blissfully thinking of a circus parade, or some other harrnless and distant thing. VIII. THE PRESS -WORKING OF METALS. Development of Press-working. The working of metals by the aid of presses and dies must certainly be as old as the oldest coins upon which images or inscriptions occur; — that is, it must date back at least as far as the seventh century before the Christian Era. In the intervening twenty-six centuries all branches of metallurgy have advanced marvelously, and in recent years the development of the press-worker's art has been specially rapid. It has made possible the cheap, rapid, and uniform production of many of our hardware supplies and cooking utensils, as well as plate, jewelry, and numberless parts of watches, clocks, typewriters, bicycles, wagons, automobiles, sewing machines, and other familiar appurtenances of modern civilization. Description of Presses. In press-work the metal is sometimes heated, but it is more commonly worked while cold. The press by which the work is done is a machine which, in its simplest form, consists es- sentially of a bed, a ram, and a pair of specially -formed dies which are adapted to each other in such a way that when they are forced together they give a pre- determined shape to a piece of metal that is placed between them. The ram carries one of the dies (usually called the "upper die," or "punch"), and has a reciprocating motion in a line approximately at right angles to the bed, being guided so that it moves back and forth, 88 THE TRAVELERS INSURANCE COMPANY always in the same path. The bed of the machine is massive and rigid, and the side facing the ram has a perfectly true and flat surface, upon which the other die is fastened. The ram slides (or sometimes swings) within a rigid framework, and is provided with proper means for securely holding or fastening the punch or die that it bears. The ram is usually of a cylindrical or prismatic form, and slides accurately in true bearings in the frame of the press. Ram Bearings. The bearings have a great length in proportion to the size of the ram, the object being to secure rigidity, and at the same time to keep the ram in its predetermined path as accurately as possible, so that the dies may be brought together in the same Courtesy of the General Electric Company. Fig. 24. Pneumatic Feeding Device for Punch Presses. THE PRESS-WORKING OF METALS 89 Courtesy of the Eastman Kodak Company. Fig. 25. Automatic Roll-feed Press, with Feed Mechanism AND Compressed-air Ejecting Device. (The roll-feed and driving belt and pulley should be guarded.) 90 THE TRAVELERS INSURANCE COMPANY relation to each other at every operation. This is of vital importance, for otherwise the dies or the product of the machine will be injured, and the finished pieces will not be uniform in shape and size. Springing and Lost Motion. Two notable causes which destroy the accuracy of the pressing operations are false (or "lost") motions in the bearings, and spring- ing of the frame or of the ram. False motions, in a sidewise direction, will occur if the bearings of the ram are not tight enough, or if they are too short. The frame, if it is not properly designed, may spring out Fig. 26. The Walsh Guarding Device for Stamping Presses. (The two buttons on the upper surface of the central part must be pushed simultaneously in order to permit the press to operate.) of its normal shape at some point between the ram bearings and the bed; and springing of the ram itself is likely to occur, if there is insufficient metal in it, or if it projects too far out of its bearings. As a general rule it may be said that these parts of a press cannot be made too solid and substantial. Inspection and Adjustment. Presses require more care than many of the other machine-tools that are used in metal-working industries, because of the con- stantly repeated stresses and shocks to which they are subjected during their normal operation. One of the THE PRESS-WORKING OF METALS 91 Fig. 27. A Double-trip Press-operating Device, Employing Compressed Air and Two Air-valves to Actuate the Clutch. (This method of safeguarding presses is widely applicable.) 92 THE TRAVELERS INSURANCE COMPANY greatest problems in connection with them is to fasten the parts in such a way that nothing can work loose or get out of adjustment. Practically speaking, it is impossible to construct a press that will remain in good working order without attention, for any great length of time. Some of the conditions which may cause the press to get out of order are variation in speed, lack of lubrication, improper feeding, tightness of the moving parts, and variations in the load on the ram and the driving shaft. Selection of a Press. It may not be out of place, here, to state briefly some of the most essential features to be looked for when buying a pres§; — though it must be understood that presses are used for such widely different purposes that nothing but the most general counsel can be given on this subject, unless the nature of the work is stated. There should be a great excess of strength and rigidity throughout the entire construction, to avoid breakdowns and undue elastic yielding of the machine while in service. The un- supported part of the ram should be as short as practic- able, and the bearings and guides should be long, with ample surface and a shape adapted to the work. The bed and the ram should be heavy and extremely rigid in order to resist sudden shocks with the least practic- able amount of vibration or yielding. It is also highly important to have suitable adjusting arrangements, convenient and safe operating devices, and such safe- guards as the: nature of the work may require. Feeding Presses. The main hazard incidental to the working of a press occurs in the feeding opera- tion, which consists in inserting the metal between the two dies, either in the form of sheets or strips. THE PRESS-WORKING OF METALS 93 or as partially formed objects undergoing further manipulation. The feeding may be done either man- ually or mechanically, according to the nature of the work. When a mechanical feeding device is employed, it is usually automatic in action. The operator of an unguarded hand-fed press is likely, sooner or later, to lose the end of a finger or to Courtesy of the Royal Typewriter Company. Fig. 28. A Press Operated by Double-trip Hand Levers. (The press cannot be started without tripping both levers at the same time. Hence the operator cannot have either hand in a dangerous place when the ram descends.) 94 THE TRAVELERS INSURANCE COMPANY have his hand otherwise rtiutilated, and many of the hest press operators in the country have been injured in this way. However skilful the man may be, he can hardly expect to escape injury permanently, merely by his own watchfulness and care, because the number of operations that must be performed during the course of a single working day almost invariably mounts well up into the thousands. Contrary to what the inexperienced person might naturally assume, the greatest danger does not occur Courtesy of the Eastman Kodak Company. Fig. 29. Revolving and Locking Die for Punch Press. (While one die is under the press head, the other may be loaded with safety.) THE PRESS-WORKING OF METALS 95 in connection with machines that operate continuously, but in connection with presses that are stopped after each operation by an automatic clutch or otherwise, and that are started again by manipulating a lever or foot-treadle. In hand feeding, the operators often have to pass their hands between the upper and lower dies, to insert the work and remove it; and accidents fre- quently occur in consequence of the operator having formed the habit of moving his foot and hands rhythmi- cally. This increases his efficiency, but it also increases the hazard to which he is exposed, because in a certain sense it makes him a part of the machine, inasmuch as his acts become largely automatic, instead of being determined by the exercise of judgment and the will. If his attention is drawn away, or if there is a momen- tary delay in inserting or removing the work, he may unthinkingly start the ram at the wrong instant and be seriously hurt. Furthermore, the constant and monotonous repetition of the same act, with the same expected result in every case, tends to give the operator a confidence in the condition and adjustment of the machine, which may not be warranted by the facts. The press may be gradually getting out of order, and the first evidence of this may be that the ram "repeats," — that is, fails to stop at the top of its stroke, and descends again immediately, when such action is totally unexpected. Safeguards. To prevent accidents to the operators of the presses, safeguards of various types have been •designed, a few of which are shown in the accompany- ing illustrations. Compressed-air devices are sometimes used for removing light work from the presses, and in other cases it may be practicable to use devices in 96 THE TRAVELERS INSURANCE COMPANY Courtesy of the General Electric Company. Fig. 30. Hand Guard for Punch Presses. (Showing the guard in the raised position.) THE PRESS-WORKING OF METALS 97 Courtesy of the General Electric Company, m HBBpMl^,'' » L \jm^/^^^^ ^k W^W'' ' ' ^H \^J: \ 2 •41 EiflBV r---=^^-.., ■:■ '^m=^=^s^^Km m mmsm """*' ' '' : -'i-'^.'A^^^^ Fig. 31. Hand Guard for Punch Presses. (Showing the guard lowered.) 98 THE TRAVELERS INSURANCE COMPANY which suction or magnetism plays an important part. For heavier work spring ejectors and other automatic mechanical arrangements have often proved satisfac- tory. Power presses that are designed to be operated by the simultaneous use of both hands are the safest, next to those that are fed automatically. Unfortunately, with an arrangement that is designed to require the use of both hands it is sometimes possible to tie down or otherwise secure one of the operating levers, and this annuls the special protection that the two-hand con- trol is supposed to afford, inasmuch as it allows the operator to use one hand to hold or adjust the work after the machine has been set in motion. The securing of one of the hand levers in this way should be prohibited, and persons who persist in doing it should be severely penalized. When a guard is arranged, so that it comes down in front of the work, or around it, before the ram descends, the mechanism should be so arranged that the press cannot be started until the guard is in the "safe" position. Machines for staying box corners are often built so that the mechanism cannot engage the ram forcibly until the upper die is within a fraction of an inch of the work, and if the operator's fingers are in the way they arrest the die without serious conse- quences. There appears to be no reason why this excellent principle cannot be successfully applied to presses used for working thin metal. Relation of Safeguards to Production. The asser- tion has frequently been made that safety devices on presses, as well as on certain other machines, decrease production; and no doubt it would be possible to THE PRESS-WORKING OF METALS 99 substantiate this statement in a certain limited number of cases. It often happens, however, that the guard has no bearing whatever upon efficiency, and we believe that in most instances prejudice on this score against the introduction of guards has been wholly unwarranted, and that it has not been justified by the accumulated facts of experience. At all events, we hear far less, at the present time, about loss of effi- ciency from the use of safeguards. If the guards are well-designed and are appro- priate to the service to which they are put, the curtail- ment of production, if it occurs at all, is usually only temporary, and as soon as the operators become ac- customed to the new conditions, the feeling of security that they experience allows them to work at an even higher rate of speed than before, so that after a time there is often a substantial and permanent increase in production. For example, we have one case in mind in which the average output was 9,000 pieces of work per day, without guards. The shop was operated on the piecework system, and the employees opposed the projected use of guards, in the belief that their earnings would be materially reduced, — each one being sure, of course, that no accident would happen to himself, if he continued to work in the old "unhampered" way. Nevertheless, guards of a carefully considered design were installed, and after a short period of readjust- ment to the new conditions it was found that the average production had risen to 11,000 pieces per day. Reliance upon Safeguards. Although appropriate guards materially reduce the number of accidents, operators should never rnake the mistake of relying upon mechanical safety appliances too implicitly. 100 THE TRAVELERS INSURANCE COMPANY They should never take unnecessary chances, even when guards of the best obtainable kind are in place, because it is always possible for automatic devices to get out of order. Special care should be taken, after changing dies or making repairs, to see that the machine is in proper adjustment in all its parts, so that it cannot "repeat," nor imperil the operator in any other way. Order and Discipline. It is extremely important to maintain strict discipline in a plant where there are many presses, placed closely together. Otherwise the Fig. 32. The Jones Guard for Stamping Presses. (Showing the guard in the raised position.) THE PRESS-WORKING OF METALS 101 operators are likely to have their attention drawn away from their work by persons employed at adjoining machines, and accidents are likely to occur as a con- sequence. It is sometimes advisable to isolate parti- cularly dangerous machines by means of partitions or screens, in order to confine the attention of the operators as closely as possible to their own work. Illumination. Locate the presses, if possible, in such positions that the light will strike directly upon the dies; and when artificial illumination is employed, see that the lamps are of suitable candle-power, that Fig. 33. The Jones Guard for Stamping Presses. (Showing the guard lowered.) 102 THE TRAVELERS INSURANCE COMPANY they are properly located, and that reflectors are provi- ded for them, to shield the eyes of every operator so that he can always see the danger point distinctly and without strain.* Treadles. When the press is set in motion by a foot-treadle, it is often advisable to place a fixed block of suitable height beside the treadle, and close up to it. The operator who works on a press of this type usually stands or sits with one foot constantly on the treadle, and in case he inadvertently presses downward with his foot when changing his position, or at any other inappropriate time, he may start the machine when he does not mean to, and thereby cause a serious accident. The block affords him a convenient place to rest his foot when he takes it off the treadle temporarily, and its upper surface should be rough so that his foot will not readily slip on it. If a block of this kind is used, however, it must not be forgotten that the operator, in making changes in the setting of the die, or in per- forming other work about the press that should be done only when the machine is disconnected, may attempt to place his foot on the block for greater comfort or convenience, and may inadvertently place it on the treadle instead. Whether the block is used or not, the treadle should always be provided with a separate lock or stop, wholly independent of the lock that is on the belt-shifter or the clutch ; and whenever the machine is stopped for adjustment, cleaning, or any other pur- pose,- both of these locks should be immediately set in the "safe" position. This will overcome the danger to which we have referred, and will cause a corre- sponding improvement in the accident record. •The illumination problem is further considered in Section XIII (page 149). THE PRESS-WORKING OF METALS 103 Miscellaneous Suggestions. Be sure that there is ample clearance about the dies, and that they are properly set in the press. By taking care to cut away unnecessary metal from the blocks when making punches and dies for small work, many accidents may be avoided. Cleaning the dies or other parts of continuously- operating presses while the machines are in motion causes numerous accidents, and this practice should never be allowed, under any circumstances. Caution the operators against wearing loosely- Courtesy of the General Electric Company, Fig. 34. Belt Guards on Punch Presses. 104 THE TRAVELERS INSURANCE COMPANY fitting clothing, or jumpers and other garments with torn or ragged ends; and see that women operators keep their hair closely confined by means of nets or caps. Many serious and even fatal accidents have been caused by clothing and hair being caught in moving machinery and belts. Provide adequate and substantial guards for all exposed driving belts and pulleys, particularly when they are near passageways. IX. AUTOMATIC MACHINES. Development of the Automatic Machine. The successful manufacturers of to-day are giving a great deal of study to the methods employed in their plants, with a view to increased efficiency. Keen competition has forced out of business many of those who were unwilling or financially unable to adopt the most approved methods and practices, and to install labor- saving and time-saving machines and devices. Im- provements in manufacturing equipment have been marked and numerous in recent years, and in order to keep pace with them it has been necessary to scrap much valuable machinery, or to sell it for what it would bring at second-hand. The improvements in metal-working machines have been particularly noteworthy. A comparatively few years ago, with the tools then in use, the services of a skilled machinist were required to perform even the simpler operations in metal working. Especially was this true when a number of duplicate parts were re- quired, the value of which would be impaired by the slightest variation in size or style. Men who could turn out satisfactory work of this kind were in great de- mand and consequently were well paid. Now, after a ; few days' training, an unskilled workman may be put, in charge of one or more automatic machines which will produce thousands of small objects per day, ab- solutely uniform in size and style. 106 THE TRAVELERS INSURANCE COMPANY The modern "automatic screw machine," as used at present in practically all manufacturing machine shops, is not limited to the production of screws. It turns out bolts, nuts, and gear blanks, and various parts of locks, spark plugs, typewriters, and automo- biles, as well as other objects in great variety. The automatic screw machine is the result of a process of evolution. The first screws made were cut by hand with crude implements, and this laborious hand-method was followed for a great many years. In 1775, however, the first metal-working lathe was constructed and used in England, and for a long time thereafter it was employed for manufacturing screvi^s, bolts, and nuts, and duplicate parts of various kinds, although it was extremely inefficient for that particular i aws'^'^^iR i 1 1 L Ma *'■? ■ S W'^SL, t i***" t^-- 1 SF'^^W'J! C. ©K ''K i Fig. 35. An Automatic Screw Machine. (The noteworthy feature of this machine is the guard for the change gears. It is not necessary to remove this cover when manipulating the change gears, and therefore complete protection is assured at this point at all times.) AUTOMATIC MACHINES 107 kind of work, from a modern point of view. With this machine the production of small duplicate parts was limited, because a great deal of time was consumed in placing and securing the stock in position and in changing the tools, — all of which necessitated frequent starting and stopping of the lathe. These objections were overcome and better results were obtained, as regards quantity and uniformity of production, by the hand screw machine which was sub- sequently developed. With this device, the tools could be set in position and swung to the work by the operator Fig. 36. A Detail View of the Machine Shown in Fig. 35. (This shows the change gears with the protecting cover removed.) 108 THE TRAVELERS INSURANCE COMPANY without stopping the machine, and consequently a considerable saving of labor and time was effected. The automatic screw machine soon followed, and this performs, automatically and by mechanical means, the operations of feeding the stock, chucking, and bringing the tool to position. All that is required of the operator is to make sure that the tools are sharp, to keep the automatic mechanism in proper adjustment, and to supply stock to the machines. The latest de- velopment in equipment of this kind is the multiple- spindle automatic machine, which is arranged so that work may be done upon several bars of stock simultane- ously. Two tools operate on each bar, and as the work progresses the piece is autoniatically moved from one pair of tools to the next. Accidents occur in connection with automatic machines, as well as with machines of every other kind; and although the injuries are usually of a minor nature, some of them are quite serious, and occasion- ally a fatality occurs. Hence it is well worth while to consider what can be done to increase the safety of the employees, and a few of the points that should receive attention are mentioned in the following paragraphs. Handling the Stock. In a good-sized shop there may be two hundred or more automatic machines, turning into finished products perhaps forty tons of bar stock per day. The bars that are used are often as large as 3| inches in diameter and 12 feet or more in length, and a great number must be kept in stock in order to avoid delays and shut-downs. It is therefore important to have a suitable place for storing them, and to see that they are piled in a safe manner, so that they cannot roll and injure the hands or feet of the AUTOMATIC MACHINES 109 workmen. The bars should be assorted according to size, and should be kept in strong, substantial racks, so that any required size may be had without delay or inconvenience. The work of unloading the bars from the railroad cars and transporting them to the stock room is also of a more or less dangerous character. The bars should be unloaded in such a way that none of them will over- hang, or be left in such positions that they may roll or slide; and they should preferably be kept in a hori- zontal position while being unloaded. If conveyors are used, precautions should be taken to prevent the bars from rolling off them, or from interfering with the conveying mechanism in any way, or from injuring persons who may be near. Hand hoists are frequently employed, and then it is essential to see that the slings and all parts of the hoisting apparatus are kept in safe condition. Great care should also be exercised when swinging and landing the loads, to prevent the bars from slipping from the slings and falling upon persons below. General Hazards. It is highly important to pro- vide adequate guards for the gears, clutches, driving belts, and pulleys on the automatic machines, because the floors around these machines are made slippery by the cutting oil that is constantly thrown from the tools as the stream of oil strikes them. Many injuries are due to persons slipping and coming in contact with unpro- tected gears and belts. It is advisable to place sheet- metal screens about the machines to intercept the oil, but even when this precaution is taken more or less oil is likely to be spattered about. It should not be allowed to accumulate in any considerable quantity, 110 THE TRAVELERS INSURANCE COMPANY Fig. 37. A Well-arranged Automatic Machine Department. (This arrangement permits the maximum number of machines in a given space. The aisles are broad.the light is good, and orderly conditions prevail. The belts should be guarded, however.) AUTOMATIC MACHINES 111 however, but should be cleaned up promptly arid sys- tematically. Sometimes the floor about the machines is covered with tin or sheet metal, but we do not approve of this because it tends to make the floors more slippery. Oily floors should be washed daily with hot water containing strong alkaline soap. When sawdust is sprinkled upon the floor it should not be left long enough to become thoroughly saturated with oil, but should ^-changed frequently. To reduce the likelihood of slipping, the soles and heels of the shoes worn by the i^iployees should be made of leather instead of rubber. Employees should exercise all possible care while at work, and they should be forbidden to clean the ma- chines or to wipe chips from the work while the ma- chines are in motion. So far as possible, bars of stock should be of such length that they will not project beyond the ends of the extension guards of the machines. Otherwise, loose clothing may be caught and wound up on the revolving bats; or, if the bars are of small size, they may wabble about and strike persons who may be near. Substan- tial racks should be attached to the machines, or be located near them, upon which a temporary supply of bars may be kept. This is much safer than laying them upon the floor where they are likely to roll about and cause persons to fall or stumble. - Racks of this kind are shown in Fig. 38. The shafting, belts, and pulleys, underneath the slotting and threading machines, should be effectively guarded so that the clothing of the employees (parti- cularly the skirts of women operators) will not become caught. The women should keep their hair closely confined by means of caps or nets, so that it may not be 112 THE TRAVELERS INSURANCE COMPANY caught in moving machinery, and none of the operators should wear loose-fitting, torn, or ragged garments. The automatic slotting and shaving machine is quite ingenious. The screws are fed to it through a hopper, and the heads are slotted and shaved automa- tically. The chief danger, here, is that the employees Fig. 38. A Group of Automatic Machines. (Note the rack under each machine for holding a temporary supply of bar stock. Metal shields are also provided to prevent oil from being spattered about. The belts should be guarded.) may come in contact with the rapidly-revolving saw, or have their clothing caught in the shafting. Suitable guards should be installed, therefore, to avert accidents of this kind so far as possible. Heading machines are frequently used for the pro- duction of various special kinds of nails and screws. These machines use a wire stock, which is fed automa- tically from a coil. The head is formed by "upsetting" AUTOMATIC MACHINES 113 the end of the wire by a heavy blow, and at the same time the piece is cut off to the correct length. The pulleys and driving belts on a machine of this kind should be effectively guarded. This is of special impor- tance, because the machines are often set quite closely together. As a rule, the noise in this department is almost deafening, and it should be reduced as much as practicable. After coming from the heading machines the blanks are placed in tumbling barrels to be cleaned, and fre- quently the threads are formed by thread-rolling machines. The pulleys, driving belts, and balance wheels on the thread-rolling machines should be effi- ciently guarded, particularly when the space between the machines is insufficient to insure the safe passage of the employees. The tools for automatic machines must be kept in good cutting condition, and consequently they must be frequently ground. Eye-protectors should be worn by the men who do the grinding, because many injuries are caused by particles of steel or abrasive material lodging in the eyes. The dressing of the grinding wheels must also be done with the utmost caution, if accidents are to be avoided. Recovery of Cutting Oil. The method used for treating the metal chips and scraps, in order to save the large amounts of cutting oil with which they are covered, is worthy of consideration. The chips are col- lected at the various machines and transported to the cleaning and separating department. There they are placed in a centrifugal extractor which removes the oil by centrifugal force when the machine is set in motion. The extractors are operated at high speed, and it is 114 THE TRAVELERS INSURANCE COMPANY specially important to make sure, before they are started, that their covers are securely fastened in place. Serious accidents have been known to occur when these covers have become loosened and have been thrown off. Every extractor should be frequently and thorough- ly inspected, and no pains should be spared in keeping it in first-class condition. The screws or bolts holding the base of the machine to the floor should be periodically examined, because the vibration to which they are subject may cause them to work loose. The driving belt of the extractor should be provided with a standard guard of sufficient strength to withstand any blow that might be given by the belt if it should break while moving at high speed. Cuts and scratches on the hands are quite common in machine shops. All. such wounds should be immed- iately washed out with an antiseptic solution, and be properly dressed to prevent infection. This precaution is important even in the case of slight injuries, because serious cases of blood poisoning often result from small wounds that have not received suitable care. This subject receives special attention in the next section, so far as cutting oils are concerned. X. INFECTION FROM CUTTING OILS. Cutting Oils in General. In cutting metals, especially on automatic machines, it is customary to make use of so-called cutting oils, which are caused to flow over the work at the point of operation and are afterwards collected by means of a pan or tray or other form of receiver and used over again. In large plants it is quite common to pipe the used cutting fluid from the various machines in the shop into one or more settling tanks in the basement. In its passage through the machine room the oil picks up many small particles of metal and other solid matter, and when it reaches the basement it is allowed to stand until a considerable part of the suspended material has been deposited in the form of sediment. It is then filtered to remove the finer particles that still remain in suspension, and is subsequently pumped to elevated storage tanks from which it can again flow down through pipes to the machine tools. In a plant of considerable size, a large amount of oil is required for a system of this kind, and it is not un- usual for it to contain three or four thousand gallons of fluid. It is therefore important to use the fluid as long as practicable, in order to avoid the waste and expense incident to throwing it away. Soluble Oils. Lard oil was formerly in general use wherever a good cutting oil was needed. On account of its increasing cost, however, it was gradually 116 THE TRAVELERS INSURANCE COMPANY replaced by another preparation having similar physi- cal properties and called "mineral lard oil;" and this, in its turn, has now largely given way to watery fluids consisting essentially of a so-called "soluble oil," made up into an emulsion with thirty or forty times its own bulk of water. (These soluble-oil prep- arations have a milky appearance, and the composition of them is to some extent a trade secret.) A certain amount of oil is often added to the mixture to give it the exact characteristics that are needed for efficient operation, and we are told that horse oil is not un- commonly used for this purpose. It is hardly necessary to explain that sound, healthy, vigorous horses are seldom killed merely for the sake of the oil they con- tain ; and when horse oil is used in making up a cutting fluid, it is often open to a certain amount of suspicion. The oil is probably sterilized, effectively and thoroughly, by the heat to which it is subjected during extraction; but "original innocence is preferable to repentance," and we should personally prefer to be smeared with oil from some other source. Infection and Its Causes. Plants in which cutting oils are extensively used often have a great deal of trouble in the form of septic infection of injuries on the hands of the workmen, and this difficulty has been specially marked since the advent of the soluble-oil mixtures described above. Many persons believe that cutting oils develop their objectionable properties in consequence of being brought in contact with metallic iron. It is possible that a certain amount of evidence can be produced in apparent substantiation of this view, but there can be no doubt whatsoever about the main cause of the trouble being bacterial infection. INFECTION FROM CUTTING OILS 117 In the regular operation of the circulating system the same oil returns to the machines over and over again. Failing to realize this fact, the men are not as careful as they should be to keep the oil from be- coming contaminated, and often carelessly spit in the pans or trays on their machines or contaminate the contents in other ways, without giving thought to the serious consequences that may result. Such prac- tices are, of course, highly unsanitary, and they tend to inoculate the cutting fluid with harmful bacteria. In fact, we have been told of various cases in which exceedingly serious diseases have been spread in this manner. It will be observed that a single careless man who is infected with any contagious disease that could be propagated in this way is a menace to the entire shop force, or at least to that part of it which uses the cutting oil. In every shop a certain number of men will be careful to avoid doing anything to contaminate the oil; but others will disregard (or fail to appreciate) the harm that may be done to their fellow-employees by their own careless and thought- less acts. Persistent efforts should be made to dis- cover men who are likely to spread infection, either by reason of careless habits or because they have contagious diseases, and appropriate action should be taken to remove the danger. The danger that arises from these unsanitary conditions is due to the fact that the men who work on machines that make use of cutting oils usually have their hands wet with the cutting fluid all day long. It is plain that under these circumstances there is abundant opportunity for infection and blood poisoning, provided the skin on the hands is cut or 118 THE TRAVELERS INSURANCE COMPANY broken, and the cutting fluid contains bacteria or germs of other kinds. Some oil manufacturers carefully sterilize the cutting oils that they produce, in order that the fluids may be germ-free when first put in use. This is a wise precaution, but it is not radical enough. Even if the cutting fluid is perfectly free from injurious bacteria when delivered to the consumer, it can hardly fail to become highly septic soon after it is introduced into the circulating system. The temperature at which the oil is maintained in the system is one at which many kinds of bacteria thrive and multiply with notable rapidity; and a watery fluid containing (like the modern cutting oil) a moderate amount of organic matter and small quantities of mineral salts, is an ideal medium for the culture of micro-organisms in general. Comparison of Aqueous Oils and Lard Oil. A brief consideration of the subject reveals at least one plausible reason for the increased number of cases of infection under the conditions prevailing at present. The lard oil formerly used was far more viscous than the cutting fluids now commonly employed, and it was the general practice to heat it before filtering, in order to expedite the precipitation of the small metal particles and gritty substances that it contained. This heating undoubtedly destroyed many of the germs that were present in the fluid, and repeated heatings doubtless eventually caused the destruction of the spores also. The cutting oils in use to-day are not at all viscous, and when they are used practically all the solid particles that might be harmful to the ma- chines or the machine tools will gravitate to the bottom INFECTION FROM CUTTING OILS 119 of the settling tank almost as readily as in clear water. Therefore these oils are not heated to hasten the precipitation, and hence there is a correspondingly- greater likelihood of the growth of germs and con- sequent infection. Altogether too little attention is given to the conditions which promote bacterial growth. In most plants in which cutting fluids are used in accordance with the system we have outlined, it is customary to clean out the entire circulating system at intervals; but this is seldom done oftener than once in from five to eight weeks, and even then there is usually no attempt to sterilize the fluid that is left in the system, nor to improve its quality in any other way than by filtration, and by the addition of fresh material. Waterproof Dressings. When a workman has been injured about the hands so that the skin has been broken, he is supposed, especially in a shop using cutting fluids, to proceed at once to the first- aid room of the plant to have his injury dressed, in order that it may be freed from danger of infection. It is evident, however, that a dressing of this kind must be water-proof and oil-proof if it is to be really effective. It is plain that it does but little good to wash out a cut with some sort of a disinfectant and bind it up, if the man is to return to his work and have his hands wet all day with the contarninated cutting fluid, unless the dressing is of such a character that this fluid cannot again come in contact with the un- healed wound. Unless a precaution of this kind is taken, the bandage that has been applied will absorb a considerable quantity of the contaminated fluid, and in this way will keep the wound wet with it at 120 THE TRAVELERS INSURANCE COMPANY all times. Under such circumstances the intended protection may be even worse than nothing at all. The nature of the dressing should be determined by a local physician or surgeon who is familiar with the conditions prevailing in the plant under considera- tion. In a general way, however, we may say that a collodion dressing may be quite useful for a small cut or abrasion that has been carefully sterilized; and where the percentage of oil in the cutting fluid is small (as in the more modern fluids), it may be advis- able to treat the injury with carbolated vaseline or some other surgically appropriate grease that will prevent the infected region from becoming wet. In many cases, too, a rubber cot is advantageous. The local surgeon will be glad to make suggestions that will be effective in any shop with which he is familiar. What we here desire to do is simply to call attention to the importance of providing some form of dressing that will protect the injured region from contact with the cutting fluid. Sterilization by Heat. Shops in which trouble is experienced from cutting oils should not be content, however, with the application of fluid-proof dressings to injuries. They should make every effort to elim- inate the possibility of infection in the fluid itself. In doing this it is wise to see that the fluid that is used in the circulating system is sterile when it is introduced. In the preparation of a cutting fluid from a so-called soluble oil, a fairly complete degree of initial sterilization is assured by the method by which the cutting fluid is made ready for use. In doing this the soluble oil is added to a considerable quantity of water, and the mixture is either boiled or kept for INFECTION FROM CUTTING OILS 121 some little time at a temperature approaching the boiling point, and this tends towards sterilization, as we have said. Initial sterilization is far from being sufficient, however, because the cutting fluid soon becomes contaminated to a dangerous degree unless means are taken to prevent it from doing so. One of the most obvious methods of effecting sterilization Fig. 39. A Bolt-cutter with a Self-contained Oiling System. (The pump is of the plunger type, and the stroke is adjustable, which makes it possible to regu- late the flow of oil. The air chamber insures a continuous flow of oil of considerable force. After flooding the dies and the work the oil and chips pass into the upper, or chip, pan, where the chips are ' retained, while the oil drains into the reservoir. _ The reservoir is divided into two compartments, one of which acts as a settling chamber for sediment, and the other as an oil-storage chamber.) 122 THE TRAVELERS INSURANCE COMPANY consists in frequently heating the fluid up to the boiling point for a short time. This will cause the death of most of the bacteria that are present, and will thereby greatly reduce the likelihood of infection. It is hardly feasible, however, in a plant of large size, to heat the entire mass of the cutting oil to the boiling point every day or two, nor is it commercially practicable to renew the cutting fluid every few days. In an attempt to overcome this difficulty, sterilizers have been made which operate continuously or, at all events, for con- siderable periods consecutively, and receive a part of the circulating oil current. In this way some part of the cutting fluid is being sterilized at all times; and although this method is not altogether ideal, yet it is immensely better than no attempt whatever to effect sterilization. The underlying idea of the method is, that each time the cutting fluid circulates through the system a different part of it will pass through the sterilizer. The result will be that most of the fluid will pass through the sterilizer during the course of a day or two, and in this way a helpful though imperfect approximation to sterilization is effected. Use of Antiseptics. Another method that has been tried with more or less success, consists in adding to the cutting fluid an antiseptic solution that will either kill bacteria or, at all events, check their de- velopment so as to greatly diminish the danger of infection. If a sterilizing substance of this kind is added, it must be of such a nature that it will not interfere with the efficacy of the cutting fluid, nor damage the work in any way. Carbolic acid is the most natural thing to think of in this connection, and it has been used in many cases, as well as cresol, lysol. INFECTION FROM CUTTING OILS 123 and other similar substances. In Great Britain con- siderable trouble from eczema has been experienced among the men who have to have their hands wet with cutting fluids, and it has been found that the addition of one per cent, of carbolic acid to the cutting oils has stopped the trouble from eczema. This is evidently due to the bactericidal action of the carbolic acid. Care must be taken not to use an excessive Fig. 40. Oil Pump and Part of the Piping System for A Machine Having an Individual Oil-feed. IP, M o a g & iig § M taXi W JlS o ^?r ^ i .a , ■n CN lO a d hH tL, rt 156 THE TRAVELERS INSURANCE COMPANY eyes while he is in his usual working position. A par- ticularly annoying, yet typical, violation of this princi- ple consists in placing a lighting unit, with a proper reflector equipment, over a milling machine, in such a position that when a fine cut is being made the bright metallic surface will reflect the light into the workman's eye. The eff'ect is exactly the same as if the man were lying on his back and looking directly into the reflector. His vision is affected adversely, and as he is quite likely to think that the remedy consists in providing a supple- mentary local light, he usually asks for one and often receives it, — perhaps without any reflector equipment whatever. This in no sense cures the ill, but rather intensifies it, because while formerly he had one unit causing specular reflection, he will now have two, and in addition one of them will shine directly into his eyes. It is doubtful if his ability to perform his work efficiently has been increased. The chances are that it has been reduced, instead; and the likelihood of his receiving an injury has certainly been augmented. Need for Expert Advice. The conditions we have described are to be found in the majority of machine shops to-day, notwithstanding the fact that improved methods of illumination are well within the means of every shop. The remedy consists in employing a lighting expert, and equipping the building with lighting units in accordance with his specifications. A competent lighting authority will see that the lighting units are installed in such a way that there will be no serious eye-irritation, either from direct rays from the lamps, or from specular reflection; and the cost of making the changes will be negligible in comparison with the benefits obtained. These benefits are com- ILLUMINATION 157 Q < tn S H S Of. " w 5 SI Q S 1 i-i ^ tn ■"■