Abstract: A headlamp levelling system for a road vehicle, comprises an electric motor which, in use, drives a member coupled to the headlamp so as to allow the headlamp to be adjusted in a manner to vary the direction of the light beam emitted, in use, by the headlamp. The motor is connected across the terminals of an electrical supply by way of an electrical circuit including switch means and a plurality of spaced pairs of electrical contacts. The switch means has a plurality of switch positions, one for each of said pairs of contacts, and a bridging member is associated with said pairs of contacts. The contacts and the briding member undergo relative movement in response to movement of said driven member so that the bridging member bridges said pairs of contacts, in turn, in respective discrete positions of the driven member and hence of said headlamp.