During the spring of 1998, two male auto mechanics, ages 42 and 48, were killed while working under the back end of a tow truck. The men were doing routine repair work on the rear axle and differential of the truck. The back end of the truck was raised from the floor and supported by the hydraulic central arm of the wheel lift at the rear of the tow truck. One jack stand was placed under the central arm to gain more height. This is a common practice during maintenance of tow trucks, as the wheel lift hydraulics are both power-up and power-down, and therefore, are capable of raising the back of the tow truck. Older wheel lifts had 4-way operation, up-down, and in-out. This wheel lift was a newer 6-way model, which had two additional movements, tilt up, and tilt down. The wheel lift arm was tilted up slightly when the jack stand was put underneath. The parking brakes were ineffective on the truck because the rear wheels had been removed after the truck was raised. The front wheels were not chocked, therefore there was little resistance to the truck rolling backward. No additional jacks or supports were put under the truck before the men began work. As the men worked on the rear axle, they caused the truck to roll slightly backward. The jack stand slipped backwards off the tilted wheel lift, and the rear end of the truck fell to the floor, instantly killing both men underneath. Recommendations based on our investigation are as follows: 1. Vehicles must be properly supported when working under them. 2. Vehicle repair shops should implement and enforce a written safety program, which includes safe procedures for working under raised vehicles. 3. Manufacturers, auto/truck shops and tow truck owners should be educated about the hazards of using the wheel lift arm as a support for the tow truck during maintenance and repair.
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