Four workers were raising a four-ton pipe, containing a number of laterals, into position. As the laterals were being lowered to the floor, one of the chain-falls jammed because it was not directly above the load. A worker stood between the pipe and the wall to allow the chain-fall to be used without the chain binding in the sprockets. During this process, the pipe slid in a pendulum effect along the floor toward the wall. The worker’s leg was pinned between the pipe and the cement abutment, breaking it below the knee.
Side loads occur when the hoist line is not plumb over the load to be lifted. A pendulum effect is created where the load moves independently of the hoist. Side loading reduces the hoist’s capacity. Side loading can be very dangerous as it can destabilize equipment and cause structural failure or tip-over.
Double Pendulum Effect