A dock lock, or vehicle restraint, is a device at the dock face that engages a trailer, usually by hooking its rear impact guard or blocking a wheel, to stop it moving away while forklifts load or unload it.
Trailer creep and early departure are serious dock hazards: a forklift driving into a trailer that has moved away from the dock can fall from the edge. OSHA 1910.178 requires trailer brakes to be set and wheel chocks placed while forklifts board, and 1910.26 requires measures to prevent the transport vehicle from moving while employees are on the dockboard. A dock lock is an engineering control that relies less on memory than chocks alone, because it is engaged from inside and can be tied to signal lights.
Hook-style restraints grab the trailer’s rear impact guard; wheel-based restraints block a tyre and suit trailers whose guards are damaged or missing. No restraint fits every trailer, so sites need a procedure for when it cannot engage, such as chocks plus a supervisor check. Interlocks that keep the dock door or leveler from operating until the restraint is engaged reduce mistakes. The loading dock guide covers trailer creep.