Dock plate

[2][3] These various devices differ in construction, suitability to dock conditions, cost of installation, and loading capacity.

Due to their greater weight dock boards are generally transported and placed by fork lift.

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.

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.

As the name suggests, this type of leveler is contained in a recess, or pit, beneath the dock door and floor surface.

A height differential of between 17 and 18 inches generally requires a 12-foot-long (3.7 m) leveler for a petrol-engined fork lift truck.

Second: They are expensive to maintain, since they require (being below ground level and open to the air) proper drainage and protection against the weather.