Trailer coupling

The motorized trailer coupling for a motor vehicle has a rotatably mounted hitch arm (12) carrying a hitch ball. The inner end (14) of the arm defines a rotational axis and has an offset pin (17) connected to the shaft (19) of a linear drive actuator. so that as the actuator is extended or retracted, the arm is pivoted under power. The inner end of the arm has a groove which can engage with a lug (11) on the support housing to selectively lock the arm in a straight position.