Tractor drives are furnished as single speed with soft start acceleration control. A tractor drive is utilized for straight travel on bridge cranes or monorails. Tractor Drives are available with optional multi-speed inverter controls. Tractor drive propels a hoist along a bridge, or a bridge along runways. Hardened flat tread wheels are provided with all drives intended to operate on patented track. Optional features include explosion proof controls, spark resistant wheels, soft start and variable frequency drives. The tractor drive is available in a range of standard speeds, and has many optional features. It is primarily designed for indoor service.