Abstract

A parallelogram lift in which the deck rails are raised by lifting legs affixed to sliding members that slide within channels in the deck rails. Link arms pivotally connect to the deck rail to each leg, so that the deck rail lifts vertically. A single hydraulic actuator is used to actuate the legs supporting each deck rail, which ensures that the deck rail remains level during the lifting and lowering processes. In the preferred embodiment the hydraulic system is serially coupled between the hydraulic cylinders associated with each deck rail, which ensures that the displacement of hydraulic pistons raising both deck rails is synchronous so that the two deck rails are lifted at the same rate and remain horizontally aligned throughout lifting and lowering, and an incremental braking system is provided which automatically locks the deck rails into any desired elevated position, reducing the load on the hydraulic system and providing a failsafe against free-falling of the deck rails in the event of hydraulic failure.