Two operators of waste compacting units were injured, one fatally, in separate incidents when they were crushed by a container being unloaded. During normal operation, the truck backs up to the waste container and attaches a cable to the container. A winch pulls the container toward the truck so that its trunnion bar drops into the holding brackets located at the rear of the unit. The safety bars are then locked in place to hold the trunnion bar in position. As the winch raises the container, the container pivots on the trunnion bar and the garbage is transferred from the container to the compacting unit.
In both cases, our investigations concluded that the trunnion bar on one side of the container escaped its holding bracket. Unsupported on one side, the container dropped to the ground. The container rotated on the fallen trunnion bar, releasing the second trunnion bar. The container then swung freely and struck the side of the garbage truck. In one case, the trunnion bar on the container had appropriate washers welded to the end of the trunnion bar; however, the safety bars had not been engaged.
In the case of the fatality, the safety bars were engaged; however, there were no washers on the end of the trunnion bars. A severe jolt, caused by a heavy drum unloading into the truck, raised one side of the washerless trunnion bar high enough that it escaped the safety bar, resulting in the operator being crushed.