In most Rite-Hite dock levelers, a ring rolls in the curve of a lip keeper as someone walks across the deck of the dock leveler. This allows the lip assist bar attached to the ring to push the lip up. Over time, the bar connecting the ring and the lip assist bar wears out, and the ring is unable to stay on the track of the lip keeper.This indirectly prevents the lip from raising when someone pulls the pull chain. This tutorial demonstrates how to properly replace a worn lip assist bar in a Rite-Hite dock leveler.
Self-storage roll-up doors operate in a similar manner to steel-rolling door springs. Like a steel rolling door, the curtain on these doors wraps around itself as the door opens. The primary difference, however, is that steel rolling doors are made of interlocking slats, while self-storage roll-up doors are just one piece of steel. While steel rolling doors are typically found in heavier commercial and industrial environments, self-storage roll-up doors are common in self-storage facilities.