The hydraulic dock levelers bridge the gap and height difference between the dock and the trailer. They also compensate for the up and down float of the trailer bed during loading. A dock leveler includes a ramp (hinged along its rear edge) and a lip (hinged at the front of the ramp). When not in use, the dock leveler is stored in its neutral position, flush with the loading platform floor. To use a dock leveler, the operator raises the ramp and the lip swings out. With the lip extended, the operator lowers the ramp until the lip rests on the truck.
This is the most versatile of the pit style levelers. A hydraulic cylinder is used to raise and to lower the deck, while another is typically used to operate the lip.