Connecting mechanisms for towed vehicles take a variety of forms, such as clevis and tongue mechanisms, ball and socket mechanisms, pintle hook and ring mechanisms, and the like.
Ball and socket connections comprise a spherical ball extending upward from a base attached to the towing vehicle, and a receiver socket that is attached to the trailer tongue and drops over and engages the ball to make the connection. A locking mechanism prevents the ball and socket from disengaging. The socket assembly on the trailer tongue typically includes some manner of clamp mechanism that engages the ball to prevent the socket from moving out of engagement with the ball. The ball and socket connection allows horizontal and vertical relative movement between the towing and towed vehicles.
Such ball and socket hitch systems are disclosed for example in U.S. Pat. No. 5,997,025 to Wisecarver, U.S. Pat. No. 7,434,826 to Lambros, U.S. Pat. No. 8,444,169 to Katz, U.S. Pat. No. 8,342,559 to MacKarvich, U.S. Pat. No. 7,690,673 to Kraai, and U.S. Pat. No. 6,505,849 to Ebey. The systems are quite complex with numerous parts and typically include a spring to bias some part of the mechanism against the ball.