A rail gear system for attachment to the frame rails of a truck that readily accommodates the span of the frame rails. The system including an axle tube, a pivot tube, first and second spring sub-systems, and a pivot bar with an actuator plate mounted to the pivot bar. Frame rail mounting brackets are secured to the two frame rails of the truck. A primary actuator is employed to elevate the axle tube off of the rails and adjustment of the width of the frame rails is accomplished by movement of the bushings along both the pivot tube and pivot bar until the desired separation between the frame rail mounting brackets is achieved.