Trailer hitch assembly

The hollow shaft has centrally integrated axially acting locking mechanism of the bearing head, to move into engagement the positive locking contours (19,20,21) of flange and bearing head, in both active and inactive positions of the of the tow bar (3). The locking mechanism consists of a locking bolt (18) moved in the hollow shaft against a stop element (28) by an externally actuated device, and balls acting with it, which are contained in radial bores (22) in the hollow shaft. At least some of the components are of light metal. The trailer coupling has a pivoted tow bar with a hitch ball at the end, which is locked via engaging flange and tow bar bearing head. The bearing head (4) is located on a hollow shaft (8), which in turn is fastened to the flange (5).