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Safety and Health Information Bulletin
Performing maintenance work underneath the dump body of a dump truck presents extraordinary hazards to maintenance or servicing personnel. During an OSHA inspection at a heavy construction equipment maintenance shop, an employee was observed working between the elevated 4,000 pound dump body and the truck’s frame. The employee could not utilize the truck’s original “body prop” to support the dump body since the “body prop” would not position the dump body high enough for the employee to access the back of the truck. Consequently, employees place themselves under the elevated dump bed without proper protection.
A citation was issued for failing to provide lockout procedures while employees were working under the dump body and for failing to isolate and sufficiently block the dump body prior to doing work under the dump body. As a result, the employer contacted the University of Wisconsin-Madison Structures and Materials Testing Laboratory to develop truck bed brace brackets that would support loads over 47,000 lbs. This represented a significant engineering challenge and the positive outcome that resulted should be shared with other employers.
The purpose of this Safety and Health Information Bulletin (SHIB) is to:
The Occupational Safety and Health Administration (OSHA) reviewed its Integrated Management Information System (IMIS) accident data, and identified 31 accidents during the past 10 years that involved the unanticipated release or movement of an elevated truck bed. Nearly all of the accidents resulted in fatalities. OSHA urges employers whose employees service or maintain dump trucks to implement an effective Lockout/Tagout Program in general industry settings or to implement the above referenced construction standards in construction settings to prevent unintended releases or movement of the truck beds which can result in a employee’s death or serious injuries.
Typically, employee exposures occurred during routine maintenance or during troubleshooting activities. Work performed under the raised beds involved repairs to air or hydraulic lines, framework welding, electrical wires and release cables, power take-off shafts, hydraulic pumps, fuel pumps, and routine greasing. Body props were not used, or were used improperly, in a majority of the accidents. In a few cases, the props were used but they failed. Causes for the sudden movement of the dump bodies included: inadvertent control operation, inadvertently pulling a release cable, hydraulic failure, and premature reconnecting of an air line.
The following three sample OSHA cases illustrate some of the problems faced when using non-engineered dump body props. (Ref: OSHA IMIS).
Figure 1. Body props are commonly misused when raised upright without having the weight of the bed supported or braced. Body props are subject to rust and damage, and need to be properly maintained.
For problems with accessibility in using figures and illustrations in this document, please contact the Directorate of Science, Technology and Medicine at (202) 693-2300.
One reason that the props provided by the truck body manufacturers are not used, or are not used appropriately, is that when raised to the typical body prop height, there may not be sufficient accessible space to perform the needed maintenance.
Mechanics need to access the rear of the truck where damage often occurs to air or hydraulic hoses, electrical lines, control cables and hydraulic motors. To access these areas, the truck body must be moved to a higher position than is supported by the manufacturer’s prop. In these circumstances, employers often need to provide additional bracing or support. However, if not properly designed to support the weight of the dump body, these methods can be ineffective and lead to serious accidents. Employers should therefore ensure that, before making inspections, adjustments, or repairs under dump truck bodies, strong, heavy, positive supports are used to keep the dump body from inadvertently lowering.
The supports/cribbing methods shown in Figures 2 and 3 are examples of makeshift body props that do not safely support the dump body in an elevated position. Since these makeshift devices are not designed to safely support the elevated dump body they can inadvertently slip out of the truck frame while maintenance work is performed underneath the dump body.
Strong, heavy, positive supports are provided by dump bed manufacturers in the form of body props. Body props are non-adjustable and will support the dump body at only one position that is close to the maximum elevated dump angle. Therefore, the need to inspect and/or work on the dump bed at an angle other than the one provided by the body prop will require additional or alternative protection.
Truck Bed Brace Bracket for Dump Box
As a result of the significant risk of injury or death to employees working between the frame and dump box of a dump truck, one employer developed braces to secure the dump box while employees serviced areas on the rear axles, or drive lines, and repaired the air cylinders for the tailgates that was not reachable using the manufacturer’s prop. Three tests were conducted on one prototype brace at the Structures and Materials Testing Laboratory at the University of Wisconsin - Madison using a 1-million pound test machine calibrated to National Institute of Standards and Technology (NIST) traceable standards. Loads were applied to the brackets at the rate of 10,000 lbs./min. The braces successfully passed the test.
The following is an example of the prototype truck bed brace brackets (see Figures 5, 6 and 7) that were developed by the employer and can be used universally on any brand of dump box. The standard flange is 3.5 inches and the braces will fit up to a 4.5 inch channel. In addition, these braces have a handle that allows the employee to place the brace under the dump box without creating an additional hazard. The employee must rest the brace on the frame of the truck while standing next to the tires.
Manufacturers of dump trucks provide body props or braces as standard equipment but they are nonadjustable. If a higher angle is needed to access the rear of the truck, the manufacturer-provided standard prop can not be used when performing some of the service functions safely. The employer needs to specifically address the hazards of this condition and how to protect employees from these hazards. This SHIB raises awareness that the manufacturer’s standard body prop or support may not be adequate to perform certain jobs safely. The employer should determine whether the manufacturer can provide an alternative body prop that would raise the dump truck bed sufficiently to allow safe access for repairs or maintenance at the rear of the truck or otherwise ensure that the truck body is positively restrained from unexpected movement. Therefore, OSHA recommends that employers contact the manufacturer to determine if alternative body props are available, or to discuss other suitable methods to support the truck bed if the standard procedures are not possible.
The following actions can protect employees from the hazards faced when working under a raised dump truck dump body:
OSHA’s construction standard, 29 CFR 1926.600(a)(3)(i), requires that: "heavy machinery, equipment, or parts thereof which are suspended or held aloft... shall be substantially blocked or cribbed to prevent falling or shifting before employees are permitted to work under or between them.
Additionally, in general industry settings, OSHA’s standard, 29 CFR 1910.147(c)(7)(i), requires employers to "provide training to ensure that the purpose and function of the energy control program are understood by employees and that the knowledge and skills required for the safe application, usage, and removal of the energy controls are acquired by employees." Training shall include, but is not limited to, instruction in controlling hazards of heavy equipment maintenance, specific procedures, and appropriate devices.
The National Institute for Occupational Safety and Health (NIOSH) has also studied the hazards associated with dump truck maintenance. The NIOSH Fatality Assessment and Control Evaluation Program (FACE), conducted investigations to identify risk factors that contribute to workplace fatalities and it offers recommended intervention strategies to prevent future fatal workplace accidents. For information on FACE investigations related to dump trucks, see West Virginia Case Report - 00WV011-01 and West Virginia Case Report - 98WV029-01.
For additional information on the prototype truck bed body prop brace, contact OSHA’s Madison, Wisconsin area office at (608) 441-5388.
For information on the ISO standard that provides the performance criteria for truck bed supports, refer to ISO 13333:1994 Earth-moving machinery-Dumper body support and operators cab tilt support devices.