Actuator for shiftable undercarriage of tiltable trailer

Claim 1

In combination with a trailer having an elongated, tiltable bed provided with a deck and an elongated, underlying deck-supporting frame, said bed being normally disposed in a substantially horizontal, roading position, and a wheeled, bed-supporting undercarriage beneath the bed and normally disposed adjacent the rear end of the bed, said undercarriage being shiftable forwardly relative to the frame longitudinally thereof from said rear end to a bed-tilting position intermediate the front and rear ends of the bed, an undercarriage control assembly beneath the bed for shifting the undercarriage fore and aft, said assembly including: support structure suspended from the frame adjacent said front end of the bed; a double acting, primary, fluid pressure piston and cylinder unit having an elongated cylinder carried by said structure for fore and aft reciprocation longitudinally of the frame, said cylinder having a forwardmost butt end and a reciprocable, rearwardly extensible piston rod at the rearmost end of the cylinder; a coupling attaching the rod to the undercarriage; a pair of double acting, secondary, fluid pressure, piston and cylinder units alongside the primary unit, each having an elongated cylinder provided with a rearmost butt end and a reciprocable, forwardly extensible piston rod at the forwardmost end of its cylinder; means attaching the butt ends of the cylinders of the secondary units to said structure; and apparatus connecting the butt end of the cylinder of the primary unit to the rods of the secondary units whereby, upon application of fluid pressure to the cylinders, the rods of the secondary units first shift the primary unit and the undercarriage fore and aft a predetermined distance and, thereupon, the rod of the primary unit shifts the undercarriage fore and aft an additional distance.