TN295 RE No. 9190 %,. ** . . » * -0 ^ *.,,* af «* *o.T* A <. *?^T*' .G v ^ *^.T* A ^. 1> o, *o . * * A o5°* « .« ^. A^ *« "oV 11 ^d« .«6 4 *' V ^ A O^ - o « » - >■ y ^ - « . . v < vj £°* *.? <\ *'7V ^6* o5°^ - ^^?r P* *l v ^% ,*>°* . 4?^ P* ^1^% ^ »• A /Jtev '\/ :'Miii %f •*'.^%V /.c^^°o >*..i5sJ:.X /.-i^i.^ o '•"' <$ v^,«^>, A o* .•;-.-. V v^*j^/V A^»!ri:./^ ^\^fc^%. ^ ^ •*V . \r&& & V**"*V* %r^\c %*-£?*\cr \3$8?*** ' y % * |p^ •Sib** <&°* »•» -<^.-jSfe^ J>**mZ?X ^tisi&S &£&k\ o *.*S5Jk% > c^ .♦ v ^ IC 9190 Bureau of Mines Information Circular/1988 Surface Testing and Evaluation of the Conveyor Belt Service Machine By Jasinder S. Jaspal and Lawrence F. Miller UNITED STATES DEPARTMENT OF THE INTERIOR Information Circular 9190 Surface Testing and Evaluation of the Conveyor Belt Service Machine By Jasinder S. Jaspal and Lawrence F. Miller UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES T S Ary, Director Library of Congress Cataloging in Publication Data: fN 2 °6 UH r oA^° Jaspal, Jasinder S. Surface testing and evaluation of the conveyor belt service machine. (Information circular; 9190) Bibliography: p 29. Supt. of Docs. no.: I 28.27:9190. 1. Coal mines and mining— Equipment and supplies. 2. Mine haulage. 3. Belt conveyors— Testing. I. Miller, L. F. II. Title, III Series: Information circular (United States. Bureau of Mines); 9190. TN295.U4 [TN813] 622 s [622'.66] 88-600104 CONTENTS Page Abstract 1 Introduction 2 Acknowledgments 3 Design concept 3 Description of the CBSM 4 Structure 4 Tractive system 4 Hydraulic system 7 Belt winding system 9 Wire rope handling system 9 Pneumatic system 9 Work platform 10 Belt-move extension procedure 11 Belt-move retraction procedure 12 Initial aboveground and underground testing and modifications 14 Surface testing 15 Test program overview 15 Battery capability test 16 Hydraulic system heat stabilization investigation 17 Speed tests 19 Braking tests 20 Current draw test 21 Controlled tension tests 21 Static pull test 22 Tram current test 22 Tram duty cycle test 23 Belt winder time study 25 Summa ry 25 Repairs and modifications 27 Traction motor failure 27 Tram electronics modifications 28 Service brakes malfunction 28 Hydraulic pump replacement 28 Conclusions 28 References 29 Appendix A. — Conveyor belt service machine specifications 30 Appendix B. — Conveyor belt service machine repairs and modifications 32 ILLUSTRATIONS 1. Conveyor belt service machine and associated belt-move equipment 4 2. Conveyor belt service machine 5 3. Conveyor belt service machine layout 5 4. Conveyor belt service machine electrical schematic 6 5. Operator tram control station 7 6. Conveyor belt service machine hydraulic schematic 7 7. Hydraulic control station 8 8. Belt reel drive mechanism 8 9. Belt reel 9 10. Service machine belt storage capacity 10 11. Left wire rope reel 10 12. Air compressor 11 11 ILLUSTRATIONS— Continued Page 13. Work platform 12 14. Extension procedure 13 15. Tailpiece hitch 13 16. Tailpiece hitch adaptors 15 17. Conveyor belt service machine battery capability tests 17 18. Hydraulic pump and reservoir 18 19. Heat stabilization test 20 20. Tram duty cycle test course 24 21. Belt winder system 26 22. Belt pulled in ready to wind 26 23. Wound belt 27 24. Belt winder lock 29 TABLES 1. CBSM hydraulic heat stabilization test results 19 2. CBSM speed test results 20 3. CBSM braking test results 21 4. CBSM current draw test results 21 5. Belt winder controlled tension test results 22 6. Belt winder static pull test results 23 7. Tram current test results 23 8. Tram duty cycle test results 24 9. Belt winder time study results 25 UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT A ampere lb pound A/h ampere per hour Mm micrometer °F degree Fahrenheit mi/h mile per hour ft foot min minute f t 3 /min cubic foot per minute pet percent ft«lbf foot pound (force) psi pound (force) per square inch ft/s foot per second r/min revolution per minute gal gallon s second gal/min gallon per minute V volt h hour V dc volt, direct current hp horsepower yr year in inch SURFACE TESTING AND EVALUATION OF THE CONVEYOR BELT SERVICE MACHINE By Jasinder S. Jaspal 1 and Lawrence F. Miller 2 ABSTRACT In underground room-and-pillar mining methods, the sectional conveyor belts are extended or retracted periodically to maintain shuttle car tramming distance to a minimum. A conventional conveyor belt extension or retraction is a heavy, arduous job that if mecahnized, has the poten- tial to improve productivity and safety. To reduce the burden of heavy work of this activity and mechanize it, the Bureau of Mines developed a conveyor belt service machine (CBSM) through a research contract with Tractor MBA. The CBSM is a self-contained, battery-powered, rubber- tired vehicle capable of handling, storing, and transporting conveyor belting, wire rope, and associated belt structures in seams as low as 48 in. Belt extensions and retractions are accomplished by moving the tailpiece of a belt conveyor with the CBSM to the next position while dispensing or retrieving the belt, wire rope, and associated belt struc- tures. The CBSM improves the belt extensions and retractions by making them easier and faster, and it utilizes fewer workers. The CBSM was surface tested at the Bureau's Mining Equipment Test Facility (METF) to evaluate its performance and reliability. Modifica- tions were made to the CBSM to correct deficiencies found during surface testing. 1 Mining engineer, Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. ^Deputy program manager, Boeing Services International, Mining Equipment Test Facility. INTRODUCTION Most of the coal produced in U.S. un- derground coal mines is moved by belt conveyors. A belt conveyor haulage sys- tem of a mine generally consists of a main line belt conveyor, section belt conveyor, and/or gathering belt convey- ors. In room-and-pillar mining opera- tions, shuttle cars carry coal from con- tinuous miners or loaders and unload it on the tailpiece of a section conveyor. The section belt is extended, by adding sections to the conveyor, as the face moves forward in order to keep the haul- age distance for the shuttle cars to a minimum. This ensures the maximum number of trips for shuttle cars in a shift, thus increasing the shift production. During retreat operations, the section belts are shortened by removing belt sec- tions from the section belt in keeping ahead of the retreat operation. The task of extension or retraction is referred to as a belt move. The section belt tailpiece is readily movable. A normal belt move requires six to eight workers and takes 3 to 8 h. A 100-ft belt move can require handling up to 4,000 lb of materials. Since the belt move is a very labor intensive procedure, worker exposure to hazards is increased. There are many injuries associated with belt moves such as strains, sprains, lac- erations, etc. It is reasonable to ex- pect that a machine designed to perform the heavy portion of the task would re- duce the rate of these injuries. Addi- tionally, if the belt move shuts down production, the 3 to 8 h for a typical belt move becomes quite expensive. It is, therefore, also reasonable to expect that a machine designed to perform the heavy portion of the belt-move task could dramatically shorten the time required for the move. Significant cost savings could be realized through the use of this machine (5).^ •^Underlined numbers in parentheses re- fer to items in the list of references preceding the appendixes. The CBSM concept was conceived by the Bureau and was designed, fabricated, and demonstrated briefly by Tractor MBA (formerly MB Associates) in conjunction with West Virginia Armature Co. under Bu- reau contract J0333926 (2). The CBSM is a self-contained battery- powered vehicle capable of handling, storing, and transporting conveyor belt- ing, wire rope, and associated structures for sectional conveyor belts. The ma- chine has the potential to increase pro- ductivity and safety by reducing the heavy, arduous labor involved in typical belt moves. In testing, the CBSM was utilized for actual belt moves in mines of West Virginia and eastern Kentucky. The machine was used in a variety of con- ditions — thick and medium thick seams with both floor-mounted and roof-sup- ported belts, and in thin seams with floor-mounted belts. Although results using the CBSM for belt moves were prom- ising, changing conditions at the mines, e.g., new management, shutdown, etc., forced termination of the CBSM trials before a complete evaluation of the ma- chine could be made (1_, _3~4_, J3). Consequently, the Bureau entered into a cooperative agreement with United Coal Co. (UCC) for an extensive 3-yr in-mine trial and evaluation of the CBSM at the UCC Big First Mine in Kentucky. The coal seam at this mine pinched down to less than 48 in making the CBSM inoperable. As a result, this in-mine evaluation also had to be canceled prematurely. The CBSM was then brought to the Bu- reau's METF for an extensive surface test and evaluation program with the following objectives: 1. Conduct testing to evaluate the CBSM capabilities and to determine if the CBSM functions per manufacturer's design. 2. Conduct belt-move time trials on the CBSM to determine the reduction of labor and the time saved by using the CBSM. 3. Improve machine reliability and performance. 4. Prepare the CBSM for an extended in-mine trial. Surface testing of the CBSM at the METF commenced in August 1985. Final modifications to prepare the machine for in-mine trials were made in December 1986. Results of the surafce test and evaluation program indicate that the CBSM has the potential to perform successfully in an underground mine in production mode. ACKNOWLEDGMENTS The authors want to extend their sin- cere appreciation to the following em- ployees of the Bureau's Pittsburgh (PA) Research Center for their contributions to this report: William D. Mayercheck, supervisory physical scientist, for tech- nical guidance of the research project from its inception; Robert J. Evans, civil engineer, for directions during surface testing. Additionally, the au- thors want to thank Stephen B. Nesbitt, mechanical engineer, Boeing Services In- ternational, for assisting in the test and evaluation of the CBSM. DESIGN CONCEPT In the conceptual design analysis, the Bureau identified the following compo- nents that should be featured on the machine: 1. Batteries for power. 2. Semiautomatic battery charger. 3. Traction motors. 4. Hydraulic system for operation of machine components. 5. Belt handling mechanism. 6. Wire rope handling mechanism. 7. Large storage compartment for belt support structure. 8. Compressed air supply for pneumatic handtools. 9. Powered clamp hooks to connect the tailpiece to the service machine. The conceptual analysis also estab- lished the criteria that the machine should have complete mobility and be able to travel throughout the mine thus requiring four-wheel steering similar to a shuttle car. It was also determined that the machine should be able to tram in either direction from creep to up to 5 mi/h. Drawbar capacity in the area of 15,000 to 20,000 lb was also a desirable goal. In addition to the criteria established by the conceptual design, the following machine specifications were included in Tractor MBA's contract: 1. The machine would be capable of a 100-ft belt-move distance. 2. The machine would be capable of operating in 48-in seams. 3. The machine belt winder would ac- commodate belts up to 3/8 in thick by 42 in wide. 4. The machine belt storage capacity would be that amount which could be safe- ly and conveniently transported through the mine assuming 6-in top and bottom clearances. 5. Battery meter. 6. Fire extinguishing system. DESCRIPTION OF THE CBSM STRUCTURE The basic structure of the CBSM was chosen to be similar to that of a shut- tle car. The machine is 22 ft 11 in long and 10 ft 7 in wide with a ground clearance of 8 in. The overall height of the CBSM is 46 in. The CBSM has four- wheel steering on rubber-tired wheels. Figures 1, 2, and 3 are views of the machine. Appendix A lists the machine specifications. TRACTIVE SYSTEM A drawbar pull of 16,000 lb was se- lected for the CBSM based on an esti- mated weight of 32,000 lb for the fully- loaded machine, assuming a 50-pct grade ability factor. Two 30-hp, 1,750-r/min, 120-V dc series motors were chosen as the drive motors. The motors drive the CBSM through a 1.668:1 traction drive gear box. The CBSM has a final overall gear reduction of 28.98:1. The machine is powered by two 32-cell storage batteries series connected rated at 128 V, 680 A/h. The motors are controlled by a silicon controlled rectifier, dc-to-dc chopper system manufactured by Siemens-Allis. 4 This control system provides speed con- trol and dynamic braking. Figure 4 shows the electrical schematic for the CBSM. Figure 5 shows the operator tram control station. ^Reference to specific products does not imply endorsement by the Bureau of Mines. Conveyor belt service machine FIGURE 1. -Conveyor belt service machine and associated belt-move equipment. Resistor box Auxiliary hydraulic ? r controls Air reservoir Double-tapped belt winder Control box Slat conveyor Wire rope winder >perator s ■npartment FIGURE 2.-Conveyor belt service machine. Double - lapped belt winder Traction motors Wire rope winders Operator's compartment IOg FIGURE 3.-Conveyor belt service machine layout. 0) .Q o >. 0) > c o U I UJ o ■Hi-, jlsJLf. Lfifij — o - E a 5 E is i. FIGURE 5.-Operator tram control station. HYDRAULIC SYSTEM One hydraulic pump powers all of the machine's functions with the exception of the wheel drive. The pump is rated at 20 gal/min at 1,500 psi and is driven by a 20-hp, 1,800-r/min, 120-V dc motor. The capacity of the hydraulic reservoir is 18.7 gal. Hydraulic motors power the air compressor, belt reel, slat conveyor, and the wire rope reels. The steering has hydraulic assist. Hydraulic cylinders activate the grab hooks and locking pins and raise and lower the slat conveyor. Figure 6 shows the hydraulic schematic for the CBSM. Figure 7 shows the hydrau- lic control station. Service brake 42000 *) " < mf 4Q % "00- <> Parking brake Hydraulic take off 143' fa L. Impact wrenches Chipper Splice pin tool 35 -] | Slat conveyor I ,V~ " @ 2200 ^fc^lAtU f^ I -^^ lb i3» i *HSL ^ I ' : I^V^ )pe winders w Belt winders ' ♦ ' Notes: I. All components are as shown or equivalent 2 Typical pressure adjust to suit conditions. 3. Item 31 selector valves: position- I. High pressure (maximum tension) 2. Off 3. Reduced pressure (constant winding tension.) FIGURE 6.-Conveyor belt service machine hydraulic schematic. FIGURE 7.-Hydraulic control station. Belt drum end plate Belt drum mounting frame Hydraulic motor Belt hook tube Belt Chain coupling elt hook clamp FIGURE 8.-Belt reel drive mechanism. BELT WINDING SYSTEM The belt winder on the CBSM double winds the belt onto the reel. The belt winder is composed of two reels, the wire rope lead reel and the main reel. The winder has a primary motor rated at 50 r/min tension of 1,400 lb at winder has a secondary motor rated at 50 r/min tension of 2,000 lb at drive hydraulic with a maximum 1,500 psi. The drive hydraulic with a maximum 1,500 psi. To wind a belt on the reel, a belt hook tube that is connected to the wire ropes on the lead reel is paid out from the CBSM. The tube is placed inside the belt at the midcenter of the belt section that is to be wound and is clamped in place. The wire rope lead reel is then actuated to begin reeling in the wire ropes and the belt attached to them. The lead reel pulls the belt through the machine into the center of the main reel. When the belt is in place, the torque is trans- ferred to the rotation of the main reel. As the main reel rotates, the belt is wound on the reel. As the belt is wound on the reel and greater torque is re- quired to continue winding the belt under tension, the secondary drive hydraulic motor is activated. Figure 8 shows the belt reel drive mechanism. Figure 9 shows the belt reel. The belt storage capacity is that quan- tity of belt that can be stored on a 12-in-diameter roll plus the 30 ft that is stored in the machine under the slat \Belt FIGURE 9.-Belt reel. conveyor. The belt storage length capac- ity varies with both roll diameter and belt thickness. The size of belt roll that can be safely and conveniently transported through the mine is limited by floor and roof clearance. In seams under 52 in, the maximum size roll would have its center midway between the mine roof and floor. The belt roll center height is adjustable for the purpose of maximizing storage capacity. Assuming that 6-in top and bottom clearance is adequate for transporting a belt roll, the maximum belting that can be carried would be equal to the seam height minus 12 in. In seams over 52 in, the storage capacity is established by frame clear- ance limits that allow a roll diameter of 40 in. Figure 10 is a graph of the belt storage capacity in feet as a function of belt thickness and outside diameter of the roll. WIRE ROPE HANDLING SYSTEM The wire rope handling system is com- posed of two reels, one on each side of the CBSM (fig. 11). Each reel is driven by a hydraulic motor rated at 60 r/min with a maximum tension of 6,000 lb. The motors operate through 31:1 gear re- ducers. There is more than sufficient torque available for tensioning the wire ropes. Each motor is separately con- trolled by a pair of lever handle valves. One is an on-off valve and the other is for the selection of either a high or low preselected pressure. PNEUMATIC SYSTEM The pneumatic system supplies com- pressed air for hand-held air tools. The two-stage compressor is hydraulically driven and rated at 5 hp , 20 ft 3 /min at 100 psi (fig. 12). The air receiver tank has a capacity of 7.5 gal. The air pres- sure is maintained between 80 to 100 psi by the combination of an electric pres- sure switch and a normally open hydraulic on-off solenoid valve. There are female quick-coupled air connectors at each cor- ner of the vehicle. 10 01 c LU -E \- ~ LU -I 1^ 5 K Q UJ I- u- Z> o O 44 40- 36 32 28- 24 80 Belt thickness, in 0.50- ^230 ft, max for 42-in seam j. 140 160 180 200 220 240 260 SERVICE MACHINE BELT CAPACITY, ft FIGURE 10. -Service machine belt storage capacity. 280 300 FIGURE 11. -Left wire rope reel. WORK PLATFORM For the CBSM to perform as designated, it is necessary to have a work platform or worktable to hold the return belt off the ground and the feed belt apart from the return belt and above the worktable 's platform or shelf. This shelf provides a means of sliding the troughing rollers across under the feed belt. With the re- turn belt held off the ground, the wire rope support structure with the return idler can then be easily slid under the return belt. In order to demonstrate the CBSM in an aboveground belt move, it was necessary to construct a tailpiece to be used for the demonstration. The original design of the work platform required that it be welded to the outby end of the tailpiece. The work platform presently being used with the CBSM is of a later design and does not require welding to the tail- piece. It is a free standing assembly 11 FIGURE 12.-Air compressor. that is secured to the tailpiece with chains during a belt move. Figure 13 shows the work platform. the possible use of a bridge for roof supported structures rather than the work table for roller installation.) BELT-MOVE EXTENSION PROCEDURE Figure 14 is a visualization of the intended use of the CBSM and accessories during a belt-move extension procedure in a low-seam-height mine entry. Figure 15 shows the CBSM hooked into the tailpiece hitch. The following outlines the proposed belt-move extension procedure on a floor- supported belt system using the CBSM. (The roof-supported conveyor belt exten- sion procedure is identical except for o Position belt splice at inby end of tailpiece. o Detach conveyor system wire rope and tailpiece anchors. o Push tailpiece with CBSM toward belt drive to obtain slack in belt. o Attach conveyor system wire rope on CBSM. o Attach worktable to tailpiece. 12 12" t 12" I 8 i 33" 18" i I" in 18' 33 T 5p tz □ ._! Li ■CD 3 2" ,'■1 I. 22' ^ 55' M Ell F rd 1-1 l> HQ OH t i i !~- 1 2 M — l n ft! It M i Ji i FIGURE 13.-Work platform. o Disconnect splice at tailpiece and connect conveyor belt to belt on CBSM. o Connect and lock tailpiece to CBSM. o Install rollers while moving tail- piece and worktable with CBSM inby until belt clamp has been dispensed from CBSM. o Remove worktable and unhook belt clamp. o Pull tailpiece with CBSM until con- veyor belt is fully extended. o Assure that center of belt conforms to entryway markers. o Dismantle worktable. o Pull wire rope tight using CBSM winches. o Anchor wire rope and tailpiece to floor. NOTE: The steps or previous assump- tions may be modified to achieve the min- imum amount of time and labor necessary to complete the procedure. BELT-MOVE RETRACTION PROCEDURE The following steps outline the pro- posed belt move retraction procedure for a floor-supported conveyor belt system using the CBSM. (The roof-supported re- traction is similar. ) NOTE: The worktable is not used during the retraction belt move sequence, o Position splice connectors on con- veyor to where the midpoint of the belt to be removed is at tailpiece roller. 13 Belt storage reel CBSM Conveyor belt Top rollers y^e^a^ FIGURE 14.-Extension procedure. FIGURE 15.-Tailpiece hitch. o Detach conveyor system wire rope and tailpiece anchors. o Push tailpiece with CBSM toward drive to obtain slack in belt. o Hook belt clamp to belt and wire rope to CBSM winches. o Connect and lock tailpiece to CBSM. o While pushing the tailpiece, load the CBSM with belting, wire rope, and rollers. o When the splice is positioned be- tween the tailpiece and CBSM, detach tailpiece from CBSM. o Disconnect and load the retracted conveyor belt and reconnect conveyor belt splice. o Pull tailpiece with CBSM until con- veyor belt is fully extended. 14 o Assure the center of belt conforms to entry way markers. o Pull wire rope tight using CBSM winches. o Anchor wire rope and tailpiece to floor. NOTE: The steps or previous assump- tions may be modified to achieve the min- imum amount of time and labor necessary to complete the procedure. INITIAL ABOVEGROUND AND UNDERGROUND TESTING AND MODIFICATIONS Prior to bringing the CBSM to the METF, the machine did receive some aboveground and underground testing. The initial aboveground tests were performed at the West Virginia Armature New River manu- facturing plant. A belt extension and retraction was simulated using conveyor belting, wire rope, and belt support structures. As a result of these initial aboveground tests, a number of modifica- tions were made to the machine. The hydraulic pump was changed to increase power. The control valve system for the hydraulic hose circuits were revised to reduce back pressure in the return lines. The work platform was redesigned to be easily movable from one tail section to another. The belt winder was rebuilt to improve its wind-up capabilities. The first underground demonstration of the CBSM took place at the ARMCO Robin Hood Division, No. 9 Mine, West Virginia. The machine was used for only one belt move in this mine, but it performed ex- ceptionally well. The belt move was a 160-ft conveyor belt retraction. The ma- chine was used to wind up 320-ft of 1/4- by 36-in conveyor belting. The CBSM was used to transport this belting along with the belt's structural supports, wire rope, sail anchors, and auxiliary mate- rial to the storage area, two sections further in the mine. New management at this mine could not accommodate continued testing of the CBSM, so it was moved to ARMCO 's Big Mountain Coal Co. mine. Prior to use in this mine, the lead wire rope follower on the CBSM was redesigned to improve its function of preventing wire cross-over or overlapping on the sheave. The CBSM was used to assist in two belt moves at the Big Mountain Coal Co. mine. In the first move, the machine was used to load belting to be used in the belt extension and to move the tailpiece and lay out the belt. During the move, the CBSM had trouble moving through a bad section of floor. Overloads on the trac- tion motors caused the 400-A main fuse to blow. However, after filling the hole in the bad section of floor with timbers and replacing the fuse, the CBSM was able to complete its task. The second belt move at the Big Moun- tain Coal Co. mine was unsuccessful. The CBSM could not start because of an elec- trical fault. Additionally, a steering drag link had broken and a steering link- age pin had sheared. The CBSM, there- fore, had to be removed from the mine so that proper repairs could be made. As a result of these failures, the steering linkage pins were redesigned to provide greater strength and the drag lines were rebuilt. Also during this period, hitch adaptors (fig. 16) were de- signed and fabricated to improve the per- formance of the hitches when pushing against the tail section when moving the tail section outby. At this time, the 400-A main fuses were replaced by a cir- cuit breaker. While these modifications were being made to the CBSM, production was sus- pended at the Big Mountain Coal Co. mine. The CBSM was then taken to a UCC contract mine in Kentucky. To provide conclusive testing, the Bureau entered into a co- operative agreement with UCC for a 3-yr in-mine evaluation program for the CBSM at UCC's Big Fist Mine. At this mine, a series of five belt extensions were con- ducted using the CBSM. The machine per- formed well during these belt extensions with no major mechanical failures. Each move was made using a new inexperienced crew. Even so, the total time required for the belt extensions was reduced from 4 h for the first extension to 3 h for the fifth extension. All belt extensions were 120 ft. The time to install the belt structures was only 15 min on the 15 Tailpiece hitch adapter HI FIGURE 16.-Tailpiece hitch adaptors. fifth extension. However, when the coal seam at this mine pinched down top less than 48 in, the CBSM became inoperable. Therefore, the agreement was cancelled and the CBSM was brought to the METF for extensive surface testing and evaluation prior to any additional in-mine trials. SURFACE TESTING TEST PROGRAM OVERVIEW The original intent of the surface tri- als at the METF was to conduct capability tests and make 120-ft belt moves by the CBSM under simulated underground coal mine conditions. Extension and retrac- tion belt move tests were to be conducted simulating moves for both floor and roof- supported conveyor belt haulage systems in areas representing both low and high coal seams. A determination was to be made as to the reduction of labor and time that could be saved through the use of CBSM for belt moves. However, a prob- lem that developed early in the surface test program necessitated that the test program be altered drastically. On December 9, 1985, while undergoing battery capability testing, the left traction motor failed. Subsequent inves- tigation of the failure led to the con- clusion that this traction motor would have to be replaced. Unfortunately, a replacement motor was not received un- til July 16, 1986, and the installation was not completed until August 4, 1986. Additionally, after reinstalling the tram motor, during machine checkout, the CBSM hydraulic pump failed on August 26, 1986 and a replacement could not be installed until Septaeraber 4, 1986. Consequently, 16 approximately 9 months was lost from the test program because of the failure of these two components. During this 9- month period, minor machine refurbish- ment was proceeding but preparations for belt move testing were placed on hold. The test program was impacted further by the requirement that surface testing on the CBSM be completed by October 3, 1986. In view of the fact that less than 1 month remained in which to do any surface testing on the CBSM and that it would be impossible to complete preparations for simulated belt moves in that time, the decision was made to eliminate belt moves from the surface test program. The test program would, therefore, concentrate solely on CBSM system capability testing and preparations for in-mine testing of the CBSM. Surface tests were conducted to verify and measure the performance of the CBSM. Battery drawdown tests were conducted. Heat stabilization for the hydraulic sys- tem was checked. Tram speed, braking, and duty cycle were measured. The per- formance of the belt winder system was also investigated. Numerous modifica- tions were made to the CBSM to correct deficiencies noted during surface test- ing. A description of each test sequence follows. BATTERY CAPABILITY TEST Battery capability trials were per- formed with the objective to determine the batteries capability in providing the necessary power to conduct all required belt move procedures. The tests were conducted to determine the time required to discharge the batteries to 80 pet of full charge under idling and tramming conditions. The battery voltage was recorded on a Racal store 14 FM tape recorder. The battery level meter was removed and the voltage monitored at that point. The data tapes were played back on a Nicolett 3091 digital storage scope interfaced to a Hewlett-Packard 9845B desk top computer to produce a printout of the battery voltage versus time. A test, monitoring the battery voltage while the hydraulic drive motor and lights were energized, showed no appreci- able voltage drop. In order to simulate a realistic load on the batteries, the CBSM was cribbed up and the traction motors activated to increase the load. The batteries were fully charged. For the first few minutes of each test, only the hydraulic drive motor (120 V dc, 20 hp) and the machine lights were energized to load the system. At this point, the two traction drive motors (120 V dc, 30 hp each) were then energized. The time was then measured to reach the 80-pct- drawdown level for the batteries. During the first test, the battery 80- pct-drawdown point was reached at the 64-min mark. For this test the batteries had only been charged for 3.5 h prior to the test. The batteries were charged for 8 h prior to the remaining tests. The results of the remaining tests indicated that the batteries did not receive a suf- ficient charge after 3.5 h but that an 8-h charge was of sufficient length to return the batteries to their full potential. The three remaining tests were all stopped before the 80-pct battery level was reached because of a variety of rea- sons. The second test was stopped be- cause of conflicts with other project testing being performed in the same area as the CBSM testing. The third and fourth tests were stopped when a battery cable failed and when a traction motor failed. Although the last three battery tests were all terminated before the 80- pct level was reached, the testing did not indicate any shortcomings in the bat- tery power system on the machine. During the third test, the CBSM ran for 115 min with the batteries dropping only to the 86-pct level. This would seem to indi- cate that, on a full 8-h charge, suffi- cient power exists to perform all of the required belt move procedures. The prob- lems that occurred during the third and fourth tests were corrected and are con- sidered to be isolated problems that should not reoccur. Figure 17 shows the results of the four battery tests. 17 u 40 > LU 20 O < h _l o > 140 > DC UJ 120 r- r- < m 100 J L 20 40 60 80 100 120 140 20 40 60 80 100 120 140 TIME.min FIGURE 17.-Conveyor belt service machine battery capability tests. A, Test 1;B, test 2; C, test 3; D, test 4. HYDRAULIC SYSTEM HEAT STABILIZATION INVESTIGATION The objective of the heat stabilization tests was to determine if the operating temperature of the CBSM hydraulic system would stabilize at a safe level. The CBSM hydraulic system uses a variable displacement pressure compensated piston pump. The control valves are closed cen- ter. There is a solenoid-operated two- way bypass valve for use during startup of the pump motor to unload the pump dur- ing startup to allow the pump to prime. The pump is a piston type with a maximum output of 20-gal/min. The hydraulic tank capacity is approximately 18.7 gal. Fig- ure 18 shows the pump and reservoir. To perform the test, a Hedland 2 to 30 gal/min flowmeter was installed in the pump output line. A 3,000-psi pressure gage was installed to monitor the pump output pressure. A type K thermocouple was placed in the hydraulic tank through 18 FIGURE 18. -Hydraulic pump and reservoir. a breather in the top of the tank. Another type K thermocouple was used to measure ambient temperature. Two tests were run. Test 1 was run under no-load conditions with no hydraulic circuit be- ing operated. Test 2 was run with the right-hand wire rope circuit operating under very light load. The cable was not anchored and, therefore, rotated freely. Table 1 is a tabulation of the test measurements. For test 1, after approximately 36 min, the system reached 207° F. The test was terminated at this point because of the high temperature. The temperature rise was 139°. The oil temperature in the tank reached a final temperature of 137° above ambient. The tank was not even near stabilization temperature; the rate of rise was 22° per 5 min. Operating pressure of the system was 2,000 psi at a flow rate of 3 gal/min. For test 2, when operating the winch system (under no load), the flow rate was 10 to 11 gal/min and operating pressure was 325 psi. After 1 h 20 min the tank temperature reached 186° F or 112° above ambient. Tank temperature rose 103° dur- ing this period. The system was nearing stabilization; temperature rise was 2° per 5 min. Although 186° F may be an acceptable temperature, it is not known how hot the system may get under actual operation. If the temperature had stabilized at a somewhat lower temperature, it would be expected that the system would operate at a safe temperature as long as one or more circuits were operating. For this reason, the tank temperature was moni- tored during the test program in order to ascertain if a problem exists during normal system operation. During tram duty cycle testing, the maximum oil 19 TABLE 1. - CBSM hydraulic heat stabilization test results Elapsed System pressure, psi System flow, gal/min Temperature, °F time, min Oil Ambient Difference HYDRAULIC SYSTEM IDLING, NO FUNCTIONS OPERATING 0., 10. 15. 20. 25. 30. 35. 36. 2,000 2,000 2,000 2,000 2,000 2,000 2,000 67.8 67.9 92.0 136.2 157.8 180.1 202.0 207.0 69.0 68.7 69.2 69.5 69.8 69.8 69.6 69.8 -1.2 -.8 22.8 66.7 88.0 110.3 132.4 137.2 OPERATING WINCH SYSTEM UNDER NO LOAD 325 10.0 82.8 71.9 10.9 3 325 10.0 84.5 72.1 12.4 325 9.5 94.5 72.4 22.1 13 325 9.5 104.1 72.2 31.9 18 325 10.0 114.0 72.6 41.4 23 325 11.0 124.1 72.6 51.5 28 325 11.0 133.4 72.8 60.6 325 11.0 142.9 72.7 70.2 325 11.0 150.3 72.4 77.9 325 11.0 156.5 72.4 84.1 48 325 11.0 162.9 72.3 90.6 53 325 11.0 168.0 72.7 95.3 58 325 11.0 172.3 73.0 99.3 325 11.0 176.6 72.2 104.4 68 325 10.0 180.6 73.3 107.3 325 10.5 183.6 75.0 108.6 325 10.5 185.5 74.0 111.5 185.6 73.9 111.7 temperature noted was 149° F. This would seem to indicate that the hydraulic sys- tem on the CBSM is stable from a thermal standpoint to operate successfully under- ground. Figure 19 gives plots of temper- ature versus time for these tests. SPEED TESTS The objective of the CBSM speed test was to determine the ground speed of the CBSM. The CBSM was designed for a ground speed of 4 mi/h. A 100-ft section of a straight, level, and paved roadway was marked off. An observer was stationed at the end. The elapsed time the CBSM took to cover the 100-ft course was recorded with a stopwatch. Three runs were made in forward direction and three in the re- verse direction. The average speed for these six runs was 7.6 ft/s or 5.2 mi/h. The batteries were charged to approxi- mately 120 V, 94 pet of full charge at the start of the runs and approximately 117 V, 91 pet at the end of the runs. The speed of the CBSM was also checked with the CBSM climbing up a paved roadway with an approximate grade of 17 pet. An observer used a stopwatch to measure the time it took the CBSM to traverse a 50-ft section of the roadway. Three runs were made. Average speed up the grade was 3.7 ft/s or 2.5 mi/h. These runs began with the batteries at the 117-V mark and con- cluded the three runs at approximately 113 V or 88 pet. 20 Ll o UJ QT 3 I- < a: UJ CL UJ I- g< 1 ■ 1 ■ 1 - ...... • _ • • - • - • -• _ '.I.I.I. 10 20 30 20 TIME, min 40 60 80 FIGURE 19. -Heat stabilization test. A, No-load operation; B, winch circuit actuated. One run was repeated for the level road section after the batteries had been fully charged. On the level section, the CBSM averaged 7.9 ft/s or 5.4 mi/h. Ta- ble 2 tabulates the results of the speed tests. The speed tests verify that the CBSM has acceptable speed on adequately charged batteries. TABLE 2. - CBSM speed test results Trial Direction Elapsed t ime , s Battery charge, V dc 100-ft, LEVEL, PAVED ROADWAY; AV TRAM SPEED — 5.2 mi/h 1 Forward. . 12.86 120 2 . . .do. ... 11.99 NM 3 • • .do • • • • 12.21 NM 4 Reverse. . 14.43 NM 5 . . .do. ... 14.13 NM 6 • . .do. ... 13.74 117 50-ft, 17-pct AV TRAM GRADE, PAVED ROADWAY, SPEED--2.5 mi/h 7 8. • • • • y o • • • • Forward. . • . .do. . . . . . .do. ... 13.49 13.95 13.61 117 NM 113 100-ft LEVEL, PAVED ROADWAY, FULL BATTERY CHARGE; TRAM SPEED— 5.4 mi/h 10 11 Forward. . Reverse. . 12.28 13.11 128 128 NM Not measured. BRAKING TESTS The objective of the braking tests was to measure the braking capability of the CBSM. The tests were performed on a flat, paved roadway. The CBSM was trammed to full speed, 7.9 ft/s. At a predetermined point, the brakes were ap- plied. The stopping distance of the ma- chine was then measured. Three runs were made in the forward direction and three in the reverse direction. Stopping dis- tances were measured when only the ser- vice brakes were used and then when only the parking brakes were used. Using only the service brakes, the average stopping distance for the CBSM was 49.5 in or 4.1 ft. Repeating the procedure, using only the parking brake, gave an average stop- ping distance of 69.3 in or 5.8 ft. The braking system of the CBSM was also checked while the machine was descending a paved roadway with an approximate grade of 21 pet. The actual stopping distance was not measured. However, applying both service and parking brakes simultaneously locked all four wheels. Results of the braking test indicate that the CBSM brak- ing system performs in a satisfactory manner for in-mine use. Table 3 lists the results of braking tests. 21 CURRENT DRAW TEST The objective of the current draw test was to measure the current draw on the electrical system as a variety of hydrau- lic loads were actuated on the CBSM. The current was measured at the 175-A fuse in the hydraulic pump control box. The current was measured with a clamp-on ammeter, Amprobe model ACDC 1000. Flow rate was measured with a Hedland 2 to 30 gal/min flowmeter installed in the TABLE 3. - CBSM braking test results Trial Direction Stopping distance, in LEVEL, PAVED ROADWAY, SERVICE BRAKES; AV STOPPING DISTANCE— 49.5 in 1 62 46 58 4 42 47 6 42 LEVEL, PAVED ROADWAY, PARKING BRAKES; AV STOPPING DISTANCE— 69.3 in 7 71 88 71 10 61 67 58 pump output line. Pressure was measured with the 3,000-psi pressure gage mounted on the machine. Batteries were fully charged. Voltage was measured across the positive and negative terminals in the hydraulic control case. Table 4 tabulates the results of the current draw test. As can be seen from the results, the current draw of the hy- draulic pump motor varied from a low of 44 A with no loads operating to a high of 129 A with the compressor being driven. The results of the test indicate that the measured current for the functions actu- ated were within reasonable limits and would pose no problems for the electrical system on the CBSM. CONTROLLED TENSION TESTS The objective of the controlled tension test was to measure the belt tension as it unwinds off the belt winder reel. In a belt move, controlled tension on the belt when it is being extended is desir- able. When using the worktable to hold the return belt off the ground and the feed belt apart from the return belt, some tension on the belt will permit it to slide off the worktable and not crash to the floor. This would greatly facili- tate setting the troughing idlers under the top belt. TABLE 4. CBSM current draw test results Test Condition Flow rate, gal/min System pressure, psi Current , A Voltage, V dc 1 Belt winder off, winder assist on; high pressure. No circuits actuated, hydraulic pump running. Belt winder on; dual motor on; high pressure. Compressor on; all other cir- cuits off. Belt winder on, high pressure; assist on tramming forward to reel belt in. 12 22 <2 11 NAp 450 2,000 2,000 1,550 NAp 65 44 46 129 x 60- 80 132 2 133 3 4 5 133 128 NAp NAp Not applicable. i Hydraulic motor current. 22 The design of the belt winder hydraulic system is such that a number of modes can be employed in the operation of the belt winder reel. The hydraulic drive system includes two hydraulic motors and two pressure regulating valves. One regulat- ing valve, the low-pressure valve, is ad- justable to 500 psi. The other regulat- ing valve, the high-pressure valve, is adjustable to 2,200 psi. Through the use of control valves in the system, it is possible to operate with either single or dual motors in either low or high pres- sure. The assumptions made in the design of the system are that belt winder would normally be operated with a single motor in low-pressure mode. If torque is in- sufficient, then the second motor would be actuated. If still more torque is re- quired, then the pressure setting would be switched to the high settting. To measure the belt tension, the belt was attached to a Dillon 10,000-lb dyna- mometer was anchored to columns in the miner-bolter test structure. Pressure TABLE 5. - Belt winder controlled tension test results (Drum diameter — 34 in start, 28 in final) Test Circuit pressure, psi Belt tension, 10 3 lb Start Final SINGLE MOTOR, LOW PRESSURE 1... 2... 3... 1,800-1,850 1,800-1,850 1,750-1,850 0.4 .4 .4 0.7 -0.9 .7 - .9 .7 - .9 SINGLE MOTOR, HIGH PRESSURE 4... 5... 6... 2,000-2,050 2,000-2,050 2,000-2,050 0.7 -0.8 .65- .8 .65- .75 0.75-1.15 .8 -1.15 .7 -1.0 DUAL MOTORS, LOW PRESSURE 7... 8... 9... 1,800-1,850 1,800-1,850 1,800-1,850 0.7 -0.8 .7 - .8 .7 - .8 1.1 -1.6 1.4 -1.8 1.4 -1.8 DUAL MOTORS, HIGH PRESSURE 10.. 11.. 12.. 2,000-2,050 2,000-2,050 2,000-2,050 1.0 -1.1 .9 -1.1 1.0 -1.1 1.7 -2.1 1.7 -2.05 1.8 -2.2 BELT WINDER FREE WHEELING 13.. 14.. 15.. NM NM NM 0.35-0.5 .2 - .375 .35- .45 NM Not measured. was measured on the machine-mounted pres- sure gage. The test was performed by tramming the CBSM backwards to unwind the belt. Belt tension was then read direct- ly from the dynamometer. A number of different test conditions were investi- gated — single motor, low and high pres- sure; dual motors, low and high pressure; free wheeling, etc. Table 5 lists the results of the controlled tension tests. Results of the tests indicate that the design of the CBSM is such that adequate tension can be maintained while extending the belt. Based on the hydraulic config- uration used, it is possible to select a range of tension for a given situation. STATIC PULL TEST The objective of the static pull test was to determine the tension that belt winder system would apply to the belt in a static mode, i.e., with the CBSM sta- tionary. As in the controlled tension test, a number of test conditions were investigated — single motor, low and high pressure; and dual motors, low and high pressure. As with the controlled tension test, tension was measured using a Dillon 10,000-lb dynamometer anchored to col- umns in the miner-bolter test structure. Pressure was measured on the machine- mounted pressure gage. The test was performed with the CBSM stationary. The belt winder motors were then actuated to see what tension could be applied to the belt. Table 6 lists the results of the test. A low-pressure setting of 350 psi was not sufficient to begin reeling in the belt regardless of whether the single or dual motor set up was used. Only in the high-pressure set- ting, the belt winder was capable of winding and maintaining tension on the belt. A check was not made to see if the low-pressure setting could be raised to a setting that would be sufficient to begin reeling in the belt as designed. TRAM CURRENT TEST The objective of the tram current test was to measure the current draw as the machine was trammed. The CBSM traction system is powered by two 30-hp motors 23 TABLE 6. - Belt winder static pull test results (Belt diameter — 28 in) Test Circuit pressure, psi Belt tension, lb SINGLE MOTOR, LOW PRESSURE 1 350 350 350 l 2 1 l SINGLE MOTOR, HIGH PRESSURE 4 2,050 2,050 2,050 275 5 450 400 DUAL MOTORS, LOW PRESSURE 7 350 350 350 1 8 l *0 DUAL MOTORS, HIGH PRESSURE 10 11 2,050 2,050 2,050 650 725 12 675 Unable to move belt. rated at 120 V dc, 212-A full-load cur- rent. A clamp-on ammeter, Amprobe model ACDC 1000, was used to measure current. The CBSM was trammed over a level paved roadway and up with a grade varying be- tween 17 to 21 pet. During tramming, the CBSM hydraulic pump motor was also ener- gized. The current draw of the hydraulic pump motor was measured at 44.4 A. While tramming on the level surface, the CBSM drew 275 A total or 230.6 A for the tram motors. Battery voltage was measured at 119 V. While tramming up the grade, the CBSM drew considerably more current. Full-load current was measured at 530 A of 485.6 A for the tram motors. Battery voltage while tramming up the grade was 107 V. Table 7 lists the results of the tram current test. The test indicates that the electrical system and traction drive system will perform satisfactorily in mine roadways varying in gradient up to 17 pet. In the tram conditions inves- tigated, the current measured are within the rated capacity of the batteries. TRAM DUTY CYCLE TEST The objective of the tram duty cycle test was to determine the tram duty cycle of the CBSM. To perform this test, a 2,829-ft (fig. 20) course was laid out on a paved roadway. This course included a 206-ft section of roadway with a 17-pct grade. The test involved tramming the CBSM over this course until the batteries dropped to a level low enough to prevent continued tramming. During the test, battery voltage and current draw were measured. Hydraulic oil temperature was also monitored. The air compressor was disabled for the test to reduce the loads on the system to just the traction motors and the hydraulic pump motor. Over the course of one 8-h shift, the CBSM completed 10 circuits of the course before the batteries fell to a level low enough to stop tramming. Weather, lunch breaks, and other traffic prevented the duty cycle test from being performed without interruption. Batteries were not recharged during the shift. The CBSM covered a distance of 5.4 miles on one battery charge. Only one anomaly showed up during the test. Prior to the test, the CBSM was trammed up the slope on the course in forward and reverse to detect any differences in performance. The ma- chine would not tram up the grade in re- verse. The instantaneous overloads would trip. There was no apparent reason for TABLE 7. - Tram current test results Test Condition Battery Total voltage, V dc current, A NAp .... 2 135.7 131.6 119.0 NAp 44.4 250-300 Hydraulic pump on; no load... Tram in reverse on level, 3 paved roadway. Tram up paved roadway; 17- to 21-pct grade. 106.0-108.0 510-550 NAp Not applicable. 24 Parking area Building : 54 i y / , , s , , / s / s,A / * f f / i t t f t } t } r f / » > r I Building 155 '■'''J.'ss'S Building 152 //s,,;s*ss,,,s;ssss/ s s, Finish, 2,829 ft FIGURE 20.-Tram duty cycle test course. the overloads tripping in the reverse direction and not the forward. The over- loads were adjusted to higher settings and the tripping problem was eliminated. These test results indicate that the CBSM has a tram cycle adequate for in-mine belt moves. Table 8 lists the results of the duty cycle test. TABLE 8. - Tram duty cycle test results Cycle Tramming on level Tramming up grade Hydraulic oil Voltage, V dc Current, A Voltage, V dc Current, A temperature, °F C 1 ) 1 135 125 119 118 117 115 115 114 113 110 107 125 NAp 230-270 230-260 250 250-260 245-270 250-300 250-270 240 240 245 NAp NAp 106 104 NM 98 100 96 94 92 88 81 NAp NAp 520-590 530-560 540-560 560-580 545-590 520-580 540-580 500-540 530-570 550-580 NAp NAp 131 2 137 3 4 5 NM 149 136 6 7 126 138 8 NM 9 NM 10 NM C 1 ) NAp NAp Not applicable. NM Not measured. Open circuit, 25 BELT WINDER TIME STUDY The objective of the belt winder time study was to determine the time required to perform the steps necessary to connect a belt to the belt winder reel and reel the belt onto the reel. The steps in- volved in this operation are as follows: o Latch winder drum. o Pay out cable from winder. o Install center drum on belt. note was that a single winder motor oper- ating on high pressure would not wind the belt up more than a few feet. It proved necessary to use the dual motors to wind the belt onto the reel. Use of dual motors on low pressure was not tested. Figures 21 through 23 show the belt winder system. The results of the time study indicate that the CBSM is capable of winding a belt on the reel for transport. The study also indicates that this procedure can be accomplished in a quick and safe manner. o Reel in cable. o Disengage winder drum latch. o Reel belt on winder drum. Table 9 lists the results of this time study. For this test, no attempt was made to simulate in-mine conditions. The belt was already double lapped to begin the study. As can be seen from the study re- sults, it took 3 min 45 s for the entire procedure to be performed. One item of TABLE 9. - Belt winder time study results, seconds Activity Time Latch drum NAp Pay out cable NAp Install center drum on belt 105 Reel in cable 50 Disengage drum latch NAp Reel belt on winder drum 70 Total 225 NAp Not applicable. SUMMARY The Bureau of Mines, through a contract with Tractor MBA, developed a self- contained, rubber-tired, battery-powered vehicle capable of handling, storing, and transporting conveyor belting, wire rope, and associated structures. The machine was tested underground in two mines in West Virginia and one mine in eastern Kentucky, but for very short periods. Because of short testing periods at each of these mines, the in-mine evaluation of the CBSM was inconclusive. The CBSM, therefore, was brought to the METF for an extensive surface test and evaluation. Highlights of the surface test program and evaluation follow: o The battery power system capability to power the CBSM was measured and found to be adequate. o The thermal stability of the CBSM's hydraulic system was investigated. Results indicated that the design of the hydraulic system is acceptable. o Speed tests were performed on the CBSM. The speed of the CBSM is within design specifications and suitable for in-mine use. o Braking tests were performed on the CBSM. Tests indicate that the braking system is quite adequate. o Current draw tests indicated that the CBSM's electrical system performs to specifications. o Belt winder tests indicated that the CBSM's belt winder system will perform as designed with the added flexibility of being able to choose a variety of tension ranges for belt retraction and extension. 26 «^.. '-* ; '- , «, *"" " - ' „ /', Belt moving into CBSM FIGURE 21. -Belt winder system. Belt entering for winding FIGURE 22.-Belt pulled in ready to wind. 27 Batteries Beit Belt reel \ - FIGURE 23.-Wound belt. o The is more use. tram duty cycle of the CBSM than sufficient for in-mine o The belt winder system is a quick and safe system operating to design criteria. REPAIRS AND MODIFICATIONS Numerous repairs and modifications were made to the CBSM to correct problems ob- served during surface testing. A com- plete listing is contained in appendix B. The major repairs and modifications are described below. TRACTION MOTOR FAILURE During battery capability testing, the left traction motor failed. After the motor was disassembled, it was discovered that straps used to secure the motor armature windings in place had worked loose. During operation of the motor, the straps apparently fell out and per- mitted the armature windings to make con- tact with the motor frame or pole pieces. This caused a catastrophic failure of the motor. A check of the right traction motor indicated that the straps were also loosening and that a failure of this motor was imminent. The left traction motor was replaced and the right motor refurbished. This traction motor failure highlighted the need for overload protec- tion in the tram control circuit. This modification was made and is described in the following section. 28 TRAM ELECTRONICS MODIFICATIONS SERVICE BRAKES MALFUNCTION During the investigation of the trac- tion motor failure, a number of areas of concern were discovered in the tram con- trol package. It was found that there was no specific motor overload protec- tion, neither instantaneous or thermal. The protection built into the circuit was for the protection of the tram package electronic components and not the trac- tion motors. A current limiting circuit in the tram package would limit machine current to 850 to 950 A. The traction motors are rated at 212 A each. A ther- mistor device was also located near the tram package silicon controlled rectifier to prevent high-temperature damage to the unit. However, this would do little to protect the motors. The plugging relay in the circuit was found to be bypassed and the dynamic braking resistors were missing from the machine. In an effort to provide overload pro- tection for the motors, the circuitry for the tram package was revised to incorpo- rate both thermal and instantaneous over- load protection. The instantaneous over- load circuit was adjusted to trip at 150 pet of full-load current. A new plugging relay and new braking resistor were also installed. The new overload protection is shown on the electrical schematic. During the checkout of the CBSM, it was discovered that the service brakes were not operating properly. Troubleshoot- ing of the system indicated that the brake valve would not operate properly because the brake cup could not retract far enough to clear the bleed orifice to let oil from the return line fill the master cylinder cavity. A thicker gasket was installed on the brake valve between the piston and cavity and this corrected the problem. HYDRAULIC PUMP REPLACEMENT Also during checkout of the CBSM, the pressure-compensated hydraulic pump mal- functioned. The pump would not provide the expected flow or pressure. Attempts to repair the pump with on-hand spare parts proved unsuccessful. No specific cause could be identified for the failure of the pump other than simple attrition. A replacement variable displacement pis- ton pump was installed and the hyudraulic system functioned properly. While attempting to operate the belt winder lock, it was found that it did not operate properly. Therefore, the mecha- nism was redesigned. Figure 24 shows the redesigned belt winder lock. CONCLUSIONS Although the in-mine testing of the CBSM in three different underground mines of West Virginia and Kentucky and surface testing at the Bureau's METF were brief, the CBSM was operated enough to suggest the following design changes to improve its performance: o Reduce overall size of the CBSM to improve its capability to turn sharp tight corners in underground mines. o Fabricate the worktable with a lighter material for easier underground handling. o Consolidate and centralize all con- trols for one-person operation. o Increase the power of the belt winder. o Redesign the belt winder to accommo- date belts and drums of different lengths and sizes respectively; as in some under- ground mines, the belt is moved every 200 ft or more. The redesign shall permit the removal of the wound belt in coiled configuration for storage. o Design belt guides to align the belt on the reel as it is being wound. o Reduce the power of the wire rope winches. 29 -M- / Belt winder lock FIGURE 24.-Belt winder lock. o The CBSM was tested for very short periods underground and thus its in-mine evaluation on performance remained incon- clusive. It is, therefore, recommended to test this machine in an underground mine in a production mode for an extended period to evaluate its performance and rate of reduction of injuries related to belt moves. REFERENCES 1. Coal rectory of p. 35. 2. Eirls veyor Belt Mining. Seventh New Technology. Annual Di- Feb. 1985, J. L. Development of a Con- Service Machine (contract J0333926, Tracor, MBA). BuMines OFR 78- 84, 1983, 109 pp.; NTIS PB 84-184845. 3. Mayercheck, W. D. Coal Extraction, Transportation and Logistics Technology for Underground Mining. Pres. at SME/ AIME Of f-the-Record Meeting, Monroeville, PA, Nov. 11, 1985; 14 pp.; available upon request from W. D. Mayercheck, BuMines, Pittsburgh, PA. 4. . Overview of Advanced Under- ground Coal Extraction and Transportation Equipment. Pres. at BuMines Open Indus- try Briefing, Monroeville, PA, Jan. 15, 1985; available upon request from W. D. Mayercheck, BuMines, Pittsburgh, PA. 5. Mayercheck, W. D. Overview of Con- veyor Haulage Research Projects To In- crease Productivity. Pres. at BuMines Open Industry Briefing on Mine Conveyor Haulage Safety and Productivity, Pitts- burgh, PA, July 19, 1983, and Denver, CO, July 21, 1983; available upon request from W. D. Mayercheck, BuMines, Pitts- burgh, PA. 6. U.S. Bureau of Mines. Conveyor Belt Service Machine. Technol. News, No. 206, Aug. 1984, 2 pp. 30 APPENDIX A.~ CONVEYOR BELT SERVICE MACHINE SPECIFICATIONS Main frame, overall length 275 in. Main frame, overall width 127 in. Wheelbase 104 in. Battery end overhang 73 in. Hitch end overhang 93.5 in. Tire size 10.0 by 15. Estimated weight 28,000 lb. Inside turning radius 9.5 ft. Outside turning radius 22.75 ft. Battery power 128 V, 680 A/h. Traction drive Two 30 hp at 1,750 r/min 120 V, series wound. Traction drive gear box 1 speed, 1.668:1 ratio. Braking Built-in park brake end service brake. Wheel drive 4 required. Steering capability ±22.5°. Load carrying capacity 10,000 lb each wheel. Overall gear reduction 28.98:1. Traction drive controller Silicon controlled rectifier, 1,000 A, 2 motor, with braking. Maximum drawbar capability 16,000 lb (equivalent to 50 pet fully loaded grade ability). Ground speed at 2,000 r/min 4.14 mi/h motor speed. Parking brake 50,000 fflbf at wheel drive. Steering system 4-wheel, full power, hydraulic, closed center, non-load reaction. Drive motor 20 hp at 1,800 r/min, 120 V dc, compound wound. Pump 20 gal/min at 1,500-psi pressure compensated, variable displacement piston pump. Hydraulic reservoir 18.7 gal. Filter 10 pm, throw-away, NAPA No. 1551. 31 Pneumatic system Drive Hydraulic motor. Compressor 2 stage, 5 hp , 20 ft 3 /min at 100 psi. Receiver 7.5 gal. Operating range 80 to 100 psi. Wire Rope Winders Drive Hydraulic motor. Maximum tension 6,000 lb. Maximum winding speed 60 r/min. Type Planetary gear reduction. Double-Lapped Belt Winder Primary drive Hydraulic motor. Gear reduction Enclosed spur gear. Maximum speed 50 r/min. Maximum tension 1,400 lb at 1,500 psi. Secondary drive Hydraulic motor. Maximum speed 50 r/min. Maximum tension 2,000 lb at 1,500 psi. Slat Conveyor Drive Hydraulic motor. Conveyor chain tension 6,000 lb at 1,500 psi. Maximum speed 20 r/min. Lift travel 6 in. Lift Hydraulic cylinder. Lift capacity 5,000 lb at 1,500 psi. Tail Section Hitch Type Hydraulic cylinder. Lift capability 2,000 lb per side at 1,500 psi. Lift control Individual. Lift height 10 in. 32 APPENDIX B. — CONVEYOR BELT SERVICE MACHINE REPAIRS AND MODIFICATIONS Date Repairs and modifications 08/85 Repaired electric solenoid valve that actuates pneumatic system. 10/85 Repaired coil of 2P contactor. 10/85 Rebuilt 175-A, 600-V fuse holder. 10/85 Replaced 2P contactor contacts. 10/85 Rewired hydraulic control compartment, 12/85 Replaced battery cables. 04/86 Reconditioned right traction motor and hydraulic pump motor. 08/86 Installed new left traction motor. 08/86 Installed new regulator on pneumatic system. 08/86 Replumbed hosing in operator's compartment. 08/86 Replumbed brakes hydraulics. 08/86 Repaired service brakes. 08/86 Replumbed conveyor hydraulics. 08/86 Replaced coil in hydraulic system bypass solenoid. 08/86 Replaced auxiliary contact on 2P contactor. 09/86 Installed new hydraulic pump. 09/86 Installed new overloads in tram controlled circuit. 09/86 Redesigned belt winder lock. 10/86 Replaced belt winder sprocket and chain. 11/86 Replaced belt winder coupling. U.S. GOVERNMENT PRINTING OFFICE: 1988 — 547-000/80,061 Reason Valve malfunction. Coil case split and coil lead. The fuse holder would not accommo- date new ordered for CBSM. Contacts had welded together. Miswiring was causing shorts. Existing cables had shorted out. Major performance had deteriorated. Motor failed. Existing regulator malfunctioned. Existing hose routing did not leave room for operator. Brakes were plumbed incorrectly. The brake valve was not operating properly. Conveyor was plumbed incorrectly. Coil shorted out and prevented startup of hydraulic system. Contact malfunctioned and caused 175-A fuse to blow in hydraulic pump control box. Original pump failed. Original circuit did not contain any motor protection. Original design did not work. Components failed. Do. INT.-BU.OF MINES,PGH.,PA. 28748 o c U.S. Department of the Interior Bureau of Mines— Prod, and Distr. Cochrans Mill Road P.O. Box 18070 Pittsburgh. Pa. 15236 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. 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