Dock Leveler Plate
Items are being sold for parts because they are missing various pieces.
Dock levelers are fixed to a loading dock. They comprise a simple metal plate, called a lip, that is raised from a stowed position and then lowered onto the back of the truck. Lip can be hinged or telescopic type. They are operated either manually, via a simple pull chain, or hydraulically, (most common) with an electric pump driving a piston to lift the plate and another one to move the lip.