Abstract: A trailer coupling part which comprises a housing with a ball entry opening in the housing through which in use a towing ball is entered into the housing to complete the trailer coupling. A lever, provided with a handle, is pivotal in the housing between open and closed positions. A tongue, complementary contoured to the shape of the towing ball, is pivotal on the lever. When the towing ball is in position within the housing and the lever is in its closed position, the tongue contacts the towing ball to retain the latter in position within the housing. In the absence of a towing ball within the housing, and with the lever in an open position, the tongue automatically pivots through the ball entry opening in the housing. Moving the lever to the closed position causes the tongue to take up a position closing the ball entry opening.