Abstract: A coupling mechanism for mounting on a towing vehicle comprises a pair of parallel, horizontal plates that define an opening for receiving a pin oriented perpendicular to the plates, the pin being part of an assembly adapted to be mounted on a vehicle to be towed. A pair of jaws is pivotally mounted between the plates to be movable between a closed position coupling with the pin and an open position releasing the pin. These jaws have rear faces that in the closed position define a space. A downwardly spring-urged locking member is slidably mounted for vertical movement through the upper plate between a downward, locking position in which it extends through the space between the jaw faces and into engagement with the lower plate to retain the jaws in their closed position by engagement with the jaw faces, and an upward, withdrawn position in which the jaws are permitted to move to their open position under the action of a spring to release the pin.