Abstract: To inform warehousemen that a vehicle that has arrived at a dock is situated so as to allow loading or unloading operations, the dock is equipped with a series of radio identification tags placed in succession along an access lane to the dock and it is verified by appropriate devices associated with the dock whether a locating device placed in the immediate vicinity of the vehicle and carrying readers of radio identification tags is or is not arranged at a position with respect to a given direction in relation to the succession of tags along the access lane to the dock. The locating device is advantageously implemented in the form of a restraint chock for the wheels of the vehicle or in the form of any other means for immobilizing the latter at the dock.

Abstract: A self-contained and automatic chock for immobilizing vehicles, particularly trucks in front of a loading dock, comprises a casing (18), a chock body (12) articulated (at 14) so as to pivot relative to this casing between a first retracted position and a second projecting position and a unit (16) for moving and locking the chock body between the first and second positions, arranged to coact with the casing.