Electrohydraulic Control of Hydrostatic Transmissions

Hydrostatic Transmissions have gained widespread acceptance on mobile equipment over the last decade. They offer an efficient means to transmit energy at high power levels, while maintaining smooth proportional control. In the last few years, electrohydraulic devices have become available for stroking pump and motor swashplates with small electrical signals. This capability creates almost unlimited possibilities for improved control of mobile vehicles, ranging from simple remote control of the pump swashplate to sophisticated automatic control. This paper discusses the more practical types, including steering, crossover control (pump/motor phasing), engine anti-stall control, pressure override, and constant-speed control.