Design, simulation, fabrication and testing of a low-speed high-torque (LSHT) pump/motor for a hydrostatic vehicle

Using a low-speed high-torque pump/motor to provide the speed range and torque for an automobile offers a number of advantages over using a bent axis design, combined with an integral gearbox. However, there appear to be no LSHT units commercially available that have true variable displacement capability.; A low-speed high-torque pump/motor was designed and built that could provide a direct drive for each wheel of a hydrostatic automobile. The unit used some critical parts such as the cylinder block and modified rotating case from the stock LSHT MHA125 series radial piston pump/motor. The unit was designed to provide suitable performance for a vehicle. The first prototype was built and tested to obtain more information on overall operation, balance and smoothness of operation, low-speed characteristics, and efficiencies. Based on these results, a second generation design will be developed. A wide variety of engineering design disciplines was utilized in obtaining the optimal pump/motor for a hydrostatic automobile.