Abstract: The self-steering axle assembly includes a transverse axle member extending below the vehicle frame, either forwardly or rearwardly of the vehicle rear wheels, a king pin assembly on each of the opposite, outer end portions of the axle member, a wheel rotatably mounted on each of the king pin assemblies for steering movement and a tie rod interconnecting the wheels so they steer together. The axle member is supported from the vehicle frame for pivotal movement of the king pin assemblies relative to the frame between a forward position wherein the longitudinal axes of the king pin assemblies are upwardly inclined in a rearward direction at a forward angle of less than about 30.degree. relative to a vertical plane passing through the rotational axes of the wheels and a reverse position wherein the longitudinal axes are upwardly inclined in a forward direction at an angle of less than about 30.degree..

Abstract: The auxiliary wheel assembly includes a transverse axle member extending below the vehicle frame members, either forwardly or rearwardly of the vehicle rear wheels, a king pin assembly on each of the outer end portions of the axle member, an auxiliary wheel rotatably mounted on each of the king pin assemblies for steering movement and a tie rod interconnecting the auxiliary wheels so they steer together. The axle member is carried on one end of a pair of laterally spaced arms, the other end of which is pivotally mounted on the vehicle frame member between an operating position and a retracted position.