with either loops or chains, used for attaching the dock board to the forks of the fork lift. Dock levelers are, as mentioned, fixed to the 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. Dock levelers are more expensive devices than the comparatively light-weight dock plates and dock boards. The most common form of dock leveler is the recessed, or pit, dock leveler. As the name suggests, this type of leveler is contained in a recess, or pit, beneath the dock door and floor surface. Dock levelers are stronger than dock plates and have similar ranges to dock boards, making them suitable not only for motorized fork lift trucks but also for master conveyors (for which neither dock plates or dock boards are suitable). Safety, also, is very high for this kind of product: Safety rules as EN1398 (European Standard) specifies the safety requirements for design, construction, installation, maintenance and testing of dock levelers and for safety components on dock levelers. NOTE: edge of dock levelers have fixed positions which have restricted ranges making them unsuitable for nonstandard dock heights. Because they carry heavy motorized equipment, the grade of the incline has to be shallow. The greater the height differential between truck and dock that a dock leveler can compensate for, the longer the leveler itself has to be. Moreover, the grade of the incline must not be so great that the vehicles cannot climb it. A height differential of between 7 and 8 inches generally requires a leveler for an electric palette carrier. A height differential of between 17 and 18 inches generally requires a leveler for a petrol-engined fork lift truck. Anyway, the lip has to be considered in the length of the leveler, as it is part of it. A telescopic lip (20 or 40 inches) can help to reduce the length of the leveler to 10 feet. Dock levelers (and indeed dock plates and dock boards) are used where a building has a truck-level door, i.e. a door with a floor level roughly at the same height as the