A typical loading dock of a building includes an exterior doorway with an elevated platform for transferring cargo to and from a vehicle, such as a truck or trailer. Loading docks often have various equipment to facilitate the loading and unloading operations. Examples of such equipment include dock levelers, vehicle restraints, weather barriers, lights for illuminating the vehicle's cargo bay, and fans for ventilating the cargo bay.
Common dock levelers include a deck or ramp that is pivotally hinged along its back edge to vary the height of its front edge. A retractable extension plate or lip pivots or translates outward from the deck's front edge to span the gap between the rear of the vehicle and the front edge of the deck. The deck and lip provide a bridge between the dock's elevated platform and the vehicle's bed so that personnel and material handling equipment can readily transfer cargo to and from the vehicle.
A hook-style vehicle restraint is often used to help restrain the vehicle at a safe parked position at the dock during loading and unloading operations. Such vehicle restraints have a hook that pivots or otherwise travels up and down to selectively engage and release the vehicle's rear impact guard (sometimes known as a RIG or ICC bar). A rear impact bar is a beam that extends horizontally across the rear of a vehicle, below the bed of the truck or trailer. Its primary purpose is to help prevent an automobile from under-riding the vehicle in a rear-end collision. A rear impact bar, however, also provides a convenient, sturdy structure for a hook-style restraint to reach up in front of the bar to obstruct the bar's movement away from the dock.
To help shield against weather while the vehicle is being serviced at the dock, some type of seal is usually installed around the perimeter of the building's exterior doorway. Such seals are typically installed along the upper and side edges of the doorway to help seal any air gaps that may otherwise exist between the face of the building and the rear of the vehicle. The dock leveler's lip resting upon the floor of the vehicle's cargo bay is often relied upon for sealing most of the doorway's lower edge.
During loading and unloading operations, a lamp mounted near the building's doorway can be used for illuminating the vehicle's cargo bay. Usually some type of articulated bracket supports the lamp, so the lamp's position can be adjusted to properly aim the light when in use or to move the lamp to a nonobstructing, stored position when the lamp is not in use. Depending on the temperature within the cargo bay, sometimes a fan is also installed near the building's doorway to blow ventilating air into the vehicle's cargo bay.