An improved railcar moving vehicle is capable of travel in a first rail travel mode on a railway track on rail wheels and in a second ground travel mode on ground wheels. When the rail wheels are driving the vehicle on the rails in the rail travel mode, further traction assist is achieved by lowering powered ones of the ground wheels so as to frictionally engage either the surface of the rail bed or the rails themselves with sufficient force to drivingly increase the traction of the vehicle in the rail travel mode. The powered ground wheels are preferably driven independently of each other and of the rail wheel sets in two of the preferred embodiments by independent hydrostatic motors. In the other preferred embodiment, the ground wheels are powered from the rail wheels.