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 9246 
 
 BUREAU OF MINES 
 INFORMATION CIRCULAR/1990 
 
 Assessment of Accident Risk During 
 Haulage Truck and Power Shovel 
 Maintenance and Recommendations 
 for Improved Safety 
 
 By Thomas J. Albin 
 
 U.S. BUREAU OF MINES 
 1910-1990 
 
 THE MINERALS SOURCE 
 
 *4U OF ^ 
 
Mission: As the Nation's principal conservation 
 agency, the Department of the Interior has respon- 
 sibility for most of our nationally-owned public 
 lands and natural and cultural resources. This 
 includes fostering wise use of our land and water 
 resources, protecting our fish and wildlife, pre- 
 serving the environmental and cultural values of 
 our national parks and historical places, and pro- 
 viding for the enjoyment of life through outdoor 
 recreation. The Department assesses our energy 
 and mineral resources and works to assure that 
 their development is in the best interests of all 
 our people. The Department also promotes the 
 goals of the Take Pride in America campaign by 
 encouraging stewardship and citizen responsibil- 
 ityforthe public landsand promoting citizen par- 
 ticipation in their care. The Department also has 
 a major responsibility for American Indian reser- 
 vation communities and for people who live in 
 Island Territories under U.S. Administration. 
 
Information Circular 9246 
 
 Assessment of Accident Risk During 
 Haulage Truck and Power Shovel 
 Maintenance and Recommendations 
 for Improved Safety 
 
 By Thomas J. Albin 
 
 UNITED STATES DEPARTMENT OF THE INTERIOR 
 Manuel Lujan, Jr., Secretary 
 
 BUREAU OF MINES 
 T S Ary, Director 
 
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 Library of Congress Cataloging in Publication Data: 
 
 Albin, Thomas J. 
 
 Assessment of accident risk during haulage truck and power shovel maintenance 
 and recommendations for improved safety / by Thomas J. Albin. 
 
 p. cm. — (Information circular; 9246) 
 
 
 Includes bibliographical references. 
 
 
 Supt. of Docs, no.: I 28.27:9246. 
 
 
 1. Dump trucks — Maintenance and repair — Safety measures. 2. Mine 
 haulage — Safety measures. 3. Power shovels — Maintenance and repair — Safety 
 measures. I. Title. II. Series: Information circular (United States. Bureau of 
 Mines); 9246. 
 
 TN295.U4 [TL230.2] 622 s-dcl9 [622'.8] 
 
 88-600411 
 CIP 
 
CONTENTS 
 
 Page 
 
 Abstract 1 
 
 Introduction 2 
 
 Methods 2 
 
 Haulage truck maintenance accidents 2 
 
 Cooling system 3 
 
 Suspension system 3 
 
 Tires 3 
 
 Recommended actions for truck systems 3 
 
 Cooling system 3 
 
 Suspension system 4 
 
 Tires 5 
 
 Power shovel system accident analysis 5 
 
 Hoist and hoist cable systems 6 
 
 Swing system 6 
 
 Summary 6 
 
 ILLUSTRATION 
 
 1. Hypothetical step point on truck bumper improved with grating material 4 
 
 TABLES 
 
 1. Accident and injury ratios for truck systems 3 
 
 2. Accident and injury ratios for power shovel systems 6 
 
UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 
 
 pet percent st short ton 
 
ASSESSMENT OF ACCIDENT RISK DURING HAULAGE TRUCK 
 
 AND POWER SHOVEL MAINTENANCE AND 
 
 RECOMMENDATIONS FOR 
 
 IMPROVED SAFETY 
 
 By Thomas J. Albin 1 
 
 ABSTRACT 
 
 U.S. Bureau of Mines research has found that maintenance of surface mining equipment is involved 
 in slightly more than one-third (34.1 pet) of all surface mining accidents. Two groups of machines, 
 haulage trucks and power shovels, accounted for over one-half of all surface mining mobile equipment 
 maintenance accidents in 1978-84. Maintenance work-time histories for these machines were compared 
 with accident records to identify the most hazardous-to-maintain systems within the machines. 
 Recommendations to reduce the accident risk associated with maintenance of these hazardous systems 
 are presented. 
 
 'industrial engineer, Twin Cities Research Center, U.S. Bureau of Mines, Minneapolis, MN (now with 3M Co., St. Paul, MN). 
 
INTRODUCTION 
 
 Accidents associated with equipment maintenance 
 account for a substantial portion of all U.S. surface mining 
 accidents. Maintenance and repair operations in U.S. 
 surface mines, during the 1978-84 period, accounted for 
 34.1 pet of all lost-time accidents and 16.5 pet of all 
 fatalities. 2 This report is based on U.S. Mine Safety and 
 Health Administration (MSHA) records of maintenance 
 accidents that occurred in the surface mining industry from 
 1978 through 1984, which identify 18,331 accidents as 
 maintenance related. 3 Of these accidents, 5,776 (31.5 pet) 
 occurred during the maintenance of mobile m inin g 
 equipment. 
 
 Accidents linked to maintenance work on large haulage 
 trucks (50-st capacity or larger) constituted 21.2 pet of all 
 accidents associated with maintenance of surface mining 
 mobile equipment in the period 1978-84. During the same 
 
 period, accidents occurring during the maintenance of 
 power shovels and draglines accounted for 34.5 pet. Thus, 
 research addressing maintenance safety for these two 
 classes of equipment can potentially have an impact on 
 55.7 pet of the total number of maintenance accidents 
 involving mobile mining equipment. 
 
 As part of its mission to increase the safety of mining 
 operations, the U.S. Bureau of Mines examined 1978-84 
 MSHA maintenance accident records, including 1,225 
 accidents associated with off-road haulage trucks of 50-st 
 or larger capacity and a sample of 100 accidents from 
 approximately 2,000 associated with power shovels. This 
 report identifies highly hazardous areas of haulage truck 
 and power shovel maintenance and suggests modifications 
 to machines or procedures that would improve 
 maintenance safety. 
 
 METHODS 
 
 In order to evaluate the relative hazard of working on 
 the various systems that comprise surface mining 
 machines, the Bureau collected maintenance and repair 
 work-time records from three surface iron mines. These 
 work-time data were then classified by the system worked 
 on. Accidents that occurred during maintenance and 
 repair activity were then assigned to the same set of 
 systems. 
 
 A statistical analysis was used to evaluate the 
 contribution of each truck or shovel system to the total 
 accident frequency and injury severity, relative to the 
 portion of the total maintenance time spent maintaining or 
 repairing that system. That is, systems with a high 
 percentage of total accident frequency and a low 
 percentage of work time are highly hazardous, and systems 
 with a low percentage of total accidents and a high 
 percentage of work time are less hazardous. These 
 relative values were expressed as ratios. 
 
 The first ratio calculated was the percentage of total 
 accident frequency (total number of accidents) divided 
 by the percentage of total maintenance time spent 
 
 maintaining or repairing the particular system. The second 
 ratio calculated was the percentage of total injury severity 
 divided by the percentage of total maintenance time spent 
 maintaining or repairing the particular system. Injury 
 severity is defined as the sum of lost workdays and 
 statutory days charged, plus one-half of the restricted 
 workdays. 
 
 Statistical confidence intervals were established for 
 these ratios. Confidence intervals specify a range of values 
 around an overall mean, in this case, the overall mean of 
 a group of ratios. The more distant the severity or 
 frequency ratio of a particular system from the average of 
 all systems, the more or less hazardous the system is, 
 depending on whether the ratio is more or less than the 
 average. Those ratios that are more distant, in the sense 
 of being farther than a statistically specified distance from 
 the average of all ratios, indicate systems that are more 
 hazardous to work on than the average system. The 
 statistical technique allows a statement of confidence that 
 the systems are correctly identified as hazardous. In this 
 report, that confidence level is 95 pet. 
 
 HAULAGE TRUCK MAINTENANCE ACCIDENTS 
 
 Accidents involving haulage trucks have been analyzed 
 to determine the truck system being worked on at the time 
 of the accidents. This information, listed in table 1, was 
 obtained from MSHA accident narratives. Using 
 maintenance and repair work-time histories obtained from 
 
 Xong, D. A. An Analysis of Off-Highway Haulage Truck 
 Maintenance and Repair Accidents, 1978-84. BuMines IC 9139, 1987, 
 15 pp. 
 
 3 Work cited in footnote 2. 
 
 surface iron operations, the percentage total of all work 
 time spent in maintaining each truck system was also 
 estimated. The percentage total of all accidents in the 
 sample involving each system was then compared with the 
 percentage of work time devoted to each system to identify 
 the systems that were most hazardous. Accident frequency 
 and injury severity were both considered. 
 
 The overall average injury severity ratio for trucks was 
 1.98 days, and the overall accident frequency ratio for 
 trucks was 2.034 days. Three truck systems were identified 
 as having higher than average accident frequency and 
 
injury severity ratio: the cooling, suspension, and tire 
 systems. 
 
 Table 1. -Accident and injury ratios for truck systems 
 
 Ratio, Ratio, Pet total 
 System actual-expected actual-expected accidents 
 accident frequency Injury severity 
 
 Air 0.7698 0.2805 1.0 
 
 Blower 1.1400 .0702 .5 
 
 Box .4438 .6267 7.3 
 
 Brakes 1.5663 1.6888 6.1 
 
 Cab 1.0265 .7478 2.3 
 
 Cooling ^.8380 1 4.8102 10.5 
 
 Electric brake . .2292 .0069 .3 
 
 Electric 1.0074 .9448 5.5 
 
 Engine 1.3115 1.7010 22.1 
 
 Exhaust 1.0813 .3415 1.3 
 
 Frame .8763 .7268 6.8 
 
 Fuel 2.3140 1.4535 2.0 
 
 Hydraulic 1.1350 .5714 5.8 
 
 Fladio .4857 (2) .2 
 
 Steering 1.4872 2.4402 3.5 
 
 Suspension . . 1 8.4386 ' 10.4737 4.8 
 
 Tires 1 8.2092 1 6.7449 16.1 
 
 Wheel motors . .2228 .0184 1.3 
 
 Overall 
 
 average 2.034 1^98 NAp 
 
 NAp Not applicable. 
 
 ^cessively high accident frequency or injury severity. 
 
 Undefined. 
 
 Source: Based on MSHA accident records, 1978-84, and work- 
 time records from 3 mines. 
 
 COOLING SYSTEM 
 
 Accidents involving the cooling system were broken 
 down into two subgroups, one group of 27 that occurred in 
 the field and another group of 40 that occurred in the 
 shops. 
 
 Field accidents were predominantly (70 pet) the results 
 of opening hot cooling systems, which caused scalding by 
 the hot coolant. Another 25 pet of these accidents were 
 slip-and-fall-type accidents. All of the falls occurred 
 because of footing problems; that is, they resulted from 
 insufficient traction on the surface on which the individual 
 was standing, including deck surfaces, ladders, and tires. 
 
 Shop accidents were more diverse. A major, 
 identifiable class of accidents is falls, which accounted for 
 57 pet of all shop accidents. The falls occurring in the 
 shop also resulted, primarily, from footing problems. 
 Slipping handtools and overexertion of the worker 
 accounted for approximately 13 pet each of the accidents. 
 
 SUSPENSION SYSTEM 
 
 Of a total of 35 accidents associated with the suspension 
 system, 35 pet involved the fall of large, unsecured parts 
 on workers. In another 30 pet, workers overexerted 
 themselves, primarily while pushing or pulling on 
 wrenches. An additional 10 pet was workers' falling while 
 working on the suspension system. 
 
 TIRES 
 
 A total of 63 accidents involving tire work were 
 examined. Of these, 19 pet resulted from explosions of the 
 tire. Approximately 25 pet of the explosions occurred 
 while the tire was on the truck. Some of the explosions 
 involved the mate of the tire that was actually being 
 worked on. In most of these accidents, the injured 
 individual was struck by projectiles, either parts of the tire 
 or rim, or dust and dirt kicked up by the explosion. 
 
 Eighteen percent of the tire accidents involved the fall 
 of unsecured tires on individuals while the tires were being 
 moved. In another 2 pet of the cases, the chain or cable 
 used to secure the tire was inadequate and failed under 
 load. Thus, one of five tire accidents resulted from moving 
 inadequately secured tires. 
 
 Fourteen percent of the tire accidents involved 
 overexertion of the worker. The overexertion injuries 
 resulted from both lifting and push-pull actions. 
 
 Inadequate eye protection accounted for approximately 
 10 pet of all tire injuries, as did slipping handtools and 
 "caught in" injuries. "Caught in" injuries typically involved 
 catching a hand or fingers between a tire and the rim, or 
 between a retaining ring and the seating groove. 
 
 Falls accounted for 6 pet of the tire accidents. 
 
 RECOMMENDED ACTIONS FOR TRUCK SYSTEMS 
 
 COOLING SYSTEM 
 
 Cooling system accidents that occurred in the field are 
 predominantly the result of opening hot, pressurized 
 cooling systems. Often this appears to be the result of the 
 operator's, or less frequently the mechanic's, impatience in 
 waiting for the system to cool sufficiently before opening 
 the system for inspection or servicing. 
 
 A general approach to safety engineering is to first 
 formulate a solution to the problem. A simple solution 
 would be to develop a "sight glass" appropriate to field 
 conditions that could be added to the cooling systems. 
 This would indicate coolant levels while the system is 
 
 closed. A similar approach would be to add a transparent 
 overflow reservoir, similar to those found in automobiles, 
 which indicates fluid levels while the cooling system is 
 closed. 
 
 If impatient operators and mechanics are going to open 
 hot cooling systems, a straightforward solution to this 
 problem would be the development of a method for the 
 remote release of pressure in the cooling system. Using 
 such a device, the operator or mechanic could vent a hot 
 cooling system from a safe distance, thus avoiding 
 scaldings. If coolant loss is unacceptable, the system could 
 be modified so that it would vent into a reservoir from 
 which the coolant could be recovered. 
 
Another approach would be to install locking caps and 
 limit the distribution of keys. Kits to add locks to radiator 
 caps are available from some Original Equipment 
 Manufacturers (OEM). These are sometimes sold as 
 antivandalism kits. This would limit the number of 
 individuals who could open radiators to those who 
 presumably know the risks involved. It would also build in 
 some delay time, possibly allowing the system to cool 
 down. 
 
 A secondary approach to safety engineering is to train 
 the individuals involved to recognize hazards. Information 
 regarding the danger entailed in opening a hot cooling 
 system should be included in operator training. Finally, 
 warning signs or tags should be prominently displayed in 
 the vicinity of the cooling system. 
 
 The second most common source of accidents involving 
 field maintenance or repair of the cooling system is slips 
 and falls. The cause of these accidents can be directly 
 attributed to the condition of the surface on which the 
 individual was standing. In some cases, these surfaces 
 were inappropriate, such as tires. In other cases, they 
 were more reasonable, e.g., decks and bumpers. In all 
 cases, they involved insufficient frictional forces, primarily 
 because of lowered coefficients of friction. Frequently, this 
 decrease in friction was due to lubricants, such as fluids or 
 granular material (sand, dirt, fine ore spillage, etc.). 
 
 An engineering solution would be to identify all 
 positions where a worker might stand within a reasonable 
 reach envelope of major cooling system components. 
 These standing points could then be improved by attaching 
 grating material. This material has the advantage of 
 allowing small granular material and fluid to drain through 
 and has an intrinsically high coefficient of friction due to 
 its rough surface. A schematic of such an installation is 
 presented in figure 1. 
 
 The majority of shop accidents (57 pet) involving the 
 cooling system are falls. About two-thirds of these 
 accidents also resulted from slips while standing on truck 
 surfaces as described above, and these surfaces would 
 benefit from improved traction. About one-third of these 
 injuries in the shop resulted from the absence of railings 
 on the workstand the individual was using. Although space 
 limitations may not be as great a problem while individuals 
 work on the cooling system, this problem often prevents 
 the use of either workstands or guardrails, or both, during 
 maintenance. The development of guiderails for purchase 
 or construction of an adjustable-height workstand with 
 guardrails that could be used within confined spaces could 
 improve maintenance safety. As a starting point, such a 
 workstand could be similar to the "bucket" of a cherry 
 picker, essentially a cylinder enclosing the worker. 
 
 A second approach would be to use safety lines. 
 Attachment points for these lines could be affixed to the 
 machine. 
 
 Overexertion of the worker and slipping handtools 
 accounted for approximately 26 pet of shop accidents. 
 Because posture is often involved in such injuries, the 
 location of improved surfaces for standing so that major 
 components are within standard reach envelopes could 
 
 Figure 1 .-Hypothetical step point on truck bumper improved 
 with grating material. Detailed section (circled) shows grating. 
 
 help to reduce overexertion injuries. Trainig to avoid high- 
 risk postures would also be beneficial. 
 
 In summary, cooling system injury accidents could be 
 reduced through 
 
 1. Development of a durable sight glass or transparent 
 overflow reservoir to indicate coolant levels; 
 
 2. Development of a remotely activated pressure 
 release for haul truck radiators; 
 
 3. Purchase and installation of locking radiator caps; 
 
 4. Inclusion of warnings in the operator's and 
 mechanic's training as to the hazards of opening hot 
 cooling systems; 
 
 5. Location and improvement of the footing at 
 positions on the truck such as bumpers, decks, etc., where 
 a mechanic or operator might stand to work on or service 
 the cooling system, whether in the shop or in the field; 
 
 6. Development of a workstand with adequate railings 
 and toeboards that could be used within the confined 
 spaces of an off-road haulage truck; 
 
 7. Use of safety belts and safety lines; 
 
 8. Training for maintenance personnel in avoiding high- 
 risk postures, including lifting and push-pull exertions, 
 while exerting force. 
 
 SUSPENSION SYSTEM 
 
 Ninety-five percent of all maintenance accidents 
 involving the suspension system occurred in a shop, as 
 opposed to a field location. Thirty-five percent of 
 accidents that occurred during maintenance of the 
 suspension system resulted from unsecured parts, which 
 fell and struck workers. An additional 30 pet were 
 overexertion injuries, and 10 pet were falls. 
 
Characterization of work practices at mines with good 
 truck maintenance safety records emphasizes that the 
 suspension system components are always secured against 
 movement. One mine's procedure involves clamping the 
 suspension system component to a forklift. This gives the 
 ability to move the component as well as to secure it. This 
 mine uses a shop-fabricated bracket to clamp the system 
 component to the forklift. Development of specifications 
 and drawings for a similar fixture for dissemination to 
 mines would assist in accident prevention. Similarly, plans 
 for alternative shop-fabricated systems of securing and 
 moving suspension system components could be developed. 
 
 Falls and some overexertion injuries are related to 
 workstand characteristics. As previously mentioned, the 
 absence of railings may increase the severity of an injury, 
 and the frictional properties of the surface may increase 
 the probability of an accident. Workers exerting force 
 while assuming an awkward posture because of the height 
 of the workstand are at increased risk of an overexertion 
 injury. Workers attempting to exert the required forces 
 may slip because the workstand surface is inadequate and 
 may fall because of absent railings or toeboards. 
 
 Overexertion injuries resulting from lifting or 
 attempting to lift system components could be reduced by 
 ensuring the availability and use of lifting devices such as 
 light cranes or forklifts or other fixtures as described 
 above. Training in safe lifting techniques should also be 
 provided. 
 
 In summary, suspension system injuries could be 
 reduced by 
 
 1. Development of a fixture or fixtures to be mounted 
 on a forklift for the purpose of securing and moving 
 suspension system components; 
 
 2. Development of a similar fixture capable of 
 supporting and moving system components without the use 
 of a forklift; 
 
 3. Development of an adjustable-height workstand that 
 can be used within the confined spaces of a haulage truck 
 as previously discussed; 
 
 4. Training for workers in safe lifting and push-pull 
 procedures, including recommended postures and load 
 limits. 
 
 TIRES 
 
 Nineteen percent of all tire accidents resulted from 
 the explosion of the tire. Eighty-three percent of the 
 
 explosions could have been prevented if the tire and its 
 mate were both deflated before any work was done on 
 them, including removal from the vehicle. The 
 recommended action is to emphasize this in the training of 
 individuals who work on, or may be expected to work on 
 tires. 
 
 Eighteen percent of all tire accidents resulted from the 
 fall of tires and/or rims on workers while the tires were 
 being transported, installed, or removed from the vehicle. 
 
 Another 2 pet of all tire accidents resulted from failure 
 of the chain or cable to support the tire during movement 
 or transportation. These accidents could be prevented by 
 emphasizing the importance of supporting the tires while 
 they are being moved. Tire workers should be made 
 aware of the required chain or cable strength necessary to 
 support tires. Equipment capable of moving and 
 supporting tires should also be available for the worker's 
 use. 
 
 Overexertion injuries accounted for 14 pet of all tire 
 injuries. Training in proper lifting techniques, especially 
 when to lift and when to use a mechanical assist, should be 
 provided periodically. 
 
 Inadequate eye protection, slipping handtools, and 
 catching hands between tires and rims accounted for 30 pet 
 of all tire accidents. These accidents are best addressed 
 by changing worker behavior, which could be done through 
 training and behavioral management of safe working 
 practices. 
 
 A final 6 pet of tire accidents were falls that resulted 
 from poorly constructed workstands. The need for well- 
 designed workstands with adequate toe and guardrails has 
 already been discussed. 
 
 In summary, recommended actions for improving tire 
 safety are 
 
 1. Deflating the tires, including both tires of dual 
 mounts, prior to any work on tires; 
 
 2. Providing adequate supports for tires while they are 
 being removed, transported, or installed on trucks, and 
 developing guidelines for adequate support of cables or 
 chains; 
 
 3. Providing all tire workers appropriate training in 
 proper lifting and exerting push-pull force; 
 
 4. Ensuring that personal protective equipment, such 
 as eye protection, is used; 
 
 5. Utilizing adequate workstands, including toeboards 
 and guardrails. 
 
 POWER SHOVEL SYSTEM ACCIDENT ANALYSIS 
 
 An analysis similar to that performed on trucks was 
 conducted for accidents that occurred while working on 
 power shovels. That is, the frequency and injury severity 
 of accidents while working on various power shovel 
 systems were compared with the time spent maintaining 
 and repairing those systems. The results are presented in 
 table 2. 
 
 Three power shovel systems were identified as highly 
 hazardous in terms of the frequency of accidents relative 
 to the time spent working on the systems. These systems 
 are the hoist, hoist cable, and swing system. Two systems 
 were identified as highly hazardous in terms of the severity 
 of their associated injuries; they are the hoist cable and the 
 swing systems. 
 
Table 2. -Accident and injury ratios for power shovel systems 
 
 — Ratio, Ratio, Pet total 
 
 System actual-expected actual-expected accidents 
 
 accident frequency injury severity 
 
 Air 6\94 017 33 
 
 Boom .65 .23 7.8 
 
 Bucket .96 .61 28.1 
 
 Cab .40 .13 .6 
 
 Car body .69 1.40 5.0 
 
 Electrical 1.10 2.76 6.9 
 
 Hoist H2.37 3.55 11.5 
 
 Hoist cable .. . H3.65 '8.94 11.6 
 
 Lubrication... 1.22 1.51 4.5 
 
 Propel .25 .10 7.8 
 
 Superstructure 2.73 4.47 4.1 
 
 Swing 1 6.62 * 19.98 8.6 
 
 ^cessively high accident frequency or injury severity. 
 
 Source: Based on MSHA accident records, 1978-84, and work- 
 time records from 3 mines. 
 
 Because of the larger sample of power shovel accidents, 
 it was decided to use a random sample of power shovel 
 accident narratives, rather than examine all narratives, as 
 was done with trucks. A random sample of 100 power 
 shovel accidents was selected from all MSHA power shovel 
 accident records for the period 1978-84. The following 
 sections are based on this sample. 
 
 HOIST AND HOIST CABLE SYSTEMS 
 
 Although the hoist and hoist cable systems combined 
 account for only 1.75 pet of power shovel maintenance and 
 repair work time, 20 pet of all power shovel maintenance 
 accidents occurred while working on these two systems. 
 
 The predominant types of accidents while working on 
 the hoist and hoist cable systems are being hit by the cable 
 or flying chips (40 pet), slips and falls (30 pet), and being 
 caught in the cable (25 pet). In 6 pet of the "hit by" 
 accidents, the worker was struck by a whipping cable end. 
 In the remainder of the "hit by" accidents, chips flew off of 
 pins, etc., which were being driven with hammers. Fifty 
 
 percent of the slips and falls occurred when a worker was 
 standing on a cable drum while it was turning. The 
 remainder were due to decreased surface friction. The 
 "caught in" injuries typically involved hands or fingers 
 caught between the cable and some other object, such as 
 the drum. 
 
 The most readily addressable of these accidents appear 
 to be falls and being hit by chips. Falls have been 
 discussed in detail under truck system accidents. A 
 worker's being struck by a chip while driving a pin, etc., is 
 a very common type of power shovel accident. A potential 
 method for reducing the number of such accidents is to 
 use a soft metal hammer. A soft metal hammer would 
 reduce the number of chips and may actually be more 
 efficient than a steel hammer in converting swing energy 
 in actual work. 
 
 A second method of driving or removing pins would be 
 to utilize a hydraulic jack. In some instances, this may 
 require the development of jigs or fixtures to hold the 
 hydraulic tool in position. 
 
 SWING SYSTEM 
 
 Seven percent of all accidents in the sample involved 
 the swing system. All of these accidents occurred when an 
 object, such as a tool, fell and struck a worker below. In 
 a situation where work will be carried on at different 
 levels, any protection, such as a portable canopy, for the 
 lower-level worker would be appropriate. 
 
 Recommendations for improved safety while main- 
 taining power shovels are 
 
 1. Improved access, including better means of access, 
 and better housekeeping of walking surfaces; 
 
 2. Utilization of soft metal hammers or hydraulic tools 
 for driving or removing pins; 
 
 3. Protection from falling hand tools and from small 
 parts for workers at lower levels. 
 
 SUMMARY 
 
 Three haulage truck systems were identified as most 
 hazardous to work on in terms of both accident frequency 
 and injury severity. These systems are the cooling, the 
 suspension, and tires. Three power shovel systems were 
 identified as most hazardous in terms of accident 
 frequency. These systems were the hoist, hoist cable, and 
 the swing. Two power shovel systems, the hoist cable and 
 the swing, were identified as most hazardous in terms of 
 injury severity. Some of these accidents are amenable to 
 engineering intervention. Others may be more readily 
 addressed through behavioral intervention. 
 
 Falls are a serious type of maintenance accidents, as has 
 been seen in the analysis of these highly hazardous 
 systems. Falls accounted for approximately 25 pet of all 
 surface mine haulage truck maintenance accidents. In the 
 sample of 100 power shovel accidents, 44 pet of all 
 
 accidents involved falls, mostly from ladders. An 
 underlying theme of these falling accidents is the apparent 
 inadequacy of current workstands or other means of access 
 to the machines. Some of the design shortfalls include the 
 lack of toeboards and guardrails coupled with low-friction 
 work surfaces. Another serious problem is the space 
 constraint imposed by working within the haulage trucks 
 and power shovels. Many workstands cannot be used in 
 confined spaces. 
 
 Many falls result from inadequate footing on the 
 surfaces on which mechanics stand while performing 
 maintenance tasks. The location of such standpoints and 
 improvement of these surfaces with nonslip surfaces, such 
 as grating, would decrease the number of falling accidents, 
 as would the use of safety belts and lines. Currently, many 
 standpoints are structural elements of the machine and are 
 
surfaces on which workers stand. Spilled liquids and 
 particulate matter, which are allowed to accumulate, are 
 examples of poor housekeeping, which increases the risk 
 of a falling accident. 
 
 A second general problem is parts that are not secured. 
 The development of new workstands with toeboards 
 capable of being used within confined spaces, or the 
 utilization of existing systems with toeboards, would de- 
 crease the number of accidents where system components 
 may fall on individuals. 
 
 Finally, a large portion of all maintenance accidents 
 may be best addressed by behavioral intervention. This 
 type of behavioral intervention would consist of initial 
 training in workplace hazards and safe working methods, 
 
 followed by behavioral management strategies for 
 maintaining safe work practices. 
 
 Injuries while working on haulage trucks and power 
 shovels account for a significant portion (55.7 pet) of 
 mobile surface mining equipment maintenance accidents. 
 The systems identified within this report are the most 
 hazardous systems to maintain and repair on these 
 machines, in terms of both accident frequency and injury 
 severity. The suggested solutions to these problems are 
 primarily (1) gaining access to work areas on the 
 machines, (2) protecting the employee in the work area, 
 and (3) training the worker in safe work practices, such as 
 safe lifting techniques. 
 
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