Abstract: An axle assembly (10) is disclosed including a carrier (24) having side edges extending intermediate the frame rails (14) of a truck 12 and supports (28) secured to the frame rails (14). The carrier (24) is moved relative to the frame rails (14) by a screw (32) rotated about an axis by a hydraulic motor (36) to move a collar (40) threaded thereon and secured to the carrier (24). The carrier (24) is selectively locked in position relative to the frame rails (14) by simultaneously sliding first and second pins (44) slideably mounted to the carrier (24) into seats (58) fixed to the frame rails (14). The first ends of a pair of arms (66) are secured to an axle (60) having steerable wheels (62) while the opposite ends are pivotally mounted to the carrier (24). The arms (66) are pivoted relative to the carrier (24) by an actuator (70) to move the wheels (62) between ground-engaging and elevated positions.

Abstract: An add-on wheel/axle assembly for truck-type vehicles for reducing the effective axle load of the vehicle allowing the carrying of greater payloads without violating Governmentally imposed road restrictions. The assembly includes a hydraulically actuatable articulated arm assembly where one end of a first arm link is pivotally joined to opposed sides of the truck frame proximate its rear end and with wheels mounted on stub axles affixed to the other ends of said arm assemblies. A cross-member offset by a predetermined distance from the stub axles joins the arm assemblies together and a hydraulic cylinder is operatively coupled between the truck frame and the articulated arms for extending and retracting the wheels between a ground-engaging disposition and an elevated disposition. Further hydraulic cylinders also cooperate with the articulated arms to draw the wheels in a straddling disposition relative to the truck frame when the wheels are in their elevated disposition.