Trailer coupling

The coupling consists of a housing (15) and a ball bar inserted into the housing via an opening. The outer jacket of the ball bar has a support part (3) formed like a convex ball section. A holder part (18) on the inner jacket (19) of the housing is formed like a corresponding concave spherical cut-out. A locking element to permit insertion/withdrawal of the ball bar into/out of the housing, has a ramp-shaped contact surface (23), which in locking position engages on a ramp-shaped contact surface (22) in a cut-out (21) in the inner jacket of the housing and/or in the outer jacket of the ball bar.