Motor driven dolly actuator for semi-trailers and similar vehicles

Claim 1

A dolly assembly intended for use with a tractor-trailer type vehicle wherein the dolly assembly is provided for supporting the front end of the trailer when separated from the tractor, the dolly assembly comprising, in combination: a ring shaped collar member mounted to the bottom surface of the trailer concentric with an opening provided through the trailer bottom surface which is of a diameter not less than the diameter of the opening in the ring shaped collar member; an elongated vertically disposed cylindrically shaped supporting column having a top end, a bottom end, and vertically extending cylindrical side wall surfaces; an elongated solid cylindrically shaped rod disposed concentric with said supporting column and having a top end, a bottom end, and cylindrical side wall surfaces; said top end of said rod being affixed to said bottom end of said supporting column concentric therewith, said rod projecting vertically downwardly therefrom; an inverted U-shaped bracket having a bight portion and opposed parallel leg portions, the bight portion being affixed to said bottom end of said rod and projecting diametrically outwardly of opposite diametric portions of said rod with said leg portion extending parallel to the longitudinal axis of said rod and downward from said bottom end thereof; a pin member extending laterally between the opposite ends of said leg members and affixed thereto; a dolly wheel of a width less than the distance between said leg members and of a diameter less than the distance from said pin member to said bight portion being provided, said dolly wheel having a bore extending through the axis thereof of a diameter greater then said pin with said dolly wheel being rotatively mounted on said pin for rotation thereabout, the dolly wheel being straddled within said leg members; said top end of said support column being received in said collar member opening with said support column mounted for reciprocal vertical movement relative to said collar member for movement between a retracted position inwardly of said collar member and projecting into said trailer to raise the dolly wheel out of contact with the ground a sufficient distance to prevent any interference of the dolly wheel with the towing of the trailer when attached to the tractor, and to an operable extended position outwardly of said collar member where the dolly wheel is disposed in contact with the ground for supporting the front end of the trailer when separated from the tractor; a rack of continuous teeth formed integrally along a a longitudinal segment of said support column side walls intermediate said top and said bottom ends thereof; said rack disposed in the plane defined by said dolly wheel and said axis of said support column; a U-shaped bracket affixed to the trailer bottom surface in a position adjacent said support column and extending in a plane parallel to said plane defined by said rack of teeth, dolly wheel and support column; an air operated power driven motor mounted in said U-shaped bracket with its longitudinal axis extending normal to the plane of said bracket; a shaft extending axially outwardly of said motor to a position adjacent said rack of teeth; a cylindrically shaped gear wheel having longitudinally extending teeth defined completely about the circumference of the side walls thereof mounted concentric on the outermost end of said motor shaft with said teeth engaging the teeth of said rack; a source of air supply; a pump to maintain said source of air supply; suitable flexible tubing interconnecting said air operated motor to said source of air supply and said pump for energizing said motor; valve means connected in series relationship with said tubing intermediate said motor and said air supply and operable to direct air supply in a first direction for effecting the operation of said motor in a first direction to retract said column and raise said dolly wheel out of contact with the ground, and operable in a second position to energize said motor in a second direction to lower said column and effect engagement of said dolly wheel with the ground to support the trailer thereon; said valve means being disposed in the tractor cab to effect operation of the motor and the dolly assembly from the vehicle operator''s position in the tractor cab without the operator having to leave the cab.