directly mounted to rotate counterclockwise as viewed in fig3 and thereby elevate the spring assembly and center casting or member relative to the draw bar the operation of the apparatus will be appreciated by persons skilled in the art from the detailed description given above which contains comments on the operation as appropriate however it will be understood that the actuator for the longitudinal locking mechanism for the draw bar 14 is located between the draw bar and the bed of the truck or vehicle to which it is mounted so that it cannot be damaged in transit further it is conveniently located for actuation by a user simply by placing a hand beneath the bed of the vehicle and turning the lever 58 clockwise as seen in fig3 the latch member 64 is seated against the surface 62 of the center casting 23 as the vehicle brakes or slows down and the draw bar 14 is forced forwardly because the latch member 64 rides beneath the lever 58 against the action of the flat steel spring 65 and once the latch member 64 rides forwardly of the nose 61 on the lever 58 the lever will return to its latching position and the latch member 64 will be locked in the position shown in fig3 the mounting of the spring assembly 13 and center casting 23 and the adjustment of the spring mounting casting so as to raise the spring assembly relative to the draw bar to facilitate removal.