Patent ID: 8016069

Claim:
A control system for use with a hydrostatically driven vehicle operably associated with a variable displacement pump, the variable displacement pump connected to at least one hydraulic propel motor and generating a controllable flow of motive fluid therethrough that propels the vehicle at a travel speed, the variable displacement pump connected to the hydraulic propel motor via a fluid transfer line and to an engine via a transmission, the engine being responsive to a fueling command from an electronic control module, the control system comprising: a control connected to the variable displacement pump and operative to set a desired flow rate of the flow of motive fluid; a displacement sensor connected to the variable displacement pump and arranged to sense a displacement setting of the variable displacement pump; a pressure sensor arranged to sense a pressure of the motive fluid in the fluid transfer line; the electronic control module being configured to: receive the desired flow rate of the flow of motive fluid; receive the displacement setting from the displacement sensor; receive the pressure of motive fluid in the fluid transfer line; determine a pump load factor based on the displacement setting and the pressure; calculate engine operating parameters based on an interpolation of the pump load factor and the desired flow rate against a map of engine operating parameters; and change at least one of the fueling command of the engine, the displacement setting of the pump, and a displacement setting of the propel motor based on the calculated engine operating parameters while the travel speed is maintained substantially constant.