Abstract: An electric torque and pressure control for load sensing pumps includes a variable open circuit pump with a swash plate angle sensor. The pump is connected in line with a pressure compensated load sensing control having an electrically variable pressure relief valve and orifice. Connected to the circuit is an engine speed sensor, a user input device, and a micro-controller. The micro-controller has software that controls a pressure relief setting of the electrically variable pressure relief valve in the pressure sensing control based upon signals from the swash plate sensor and the engine speed sensor and inputs from the user input device.

Abstract: A speed control system for a hydrostatic transmission includes an engine having a drive shaft connected to a hydraulic pump. At least one hydrostatic motor is connected to the pump in a closed circuit by a flow line. Connected to the motor via a system shaft is a vehicle system. A controller is connected to a plurality of sensors and a proportional high pressure relief valve that is connected to the flow line between the pump and the motor. Based on information received from the sensors, the controller sets the pressure relief valve to limit the pressure to a valve that will not over-speed the engine and allows the demands of the speed control system to be attained. This may be accomplished through the use of various algorithms.

Abstract: A speed control system for a hydrostatic transmission includes an engine having a drive shaft connected to a hydraulic pump. At least one hydrostatic motor is connected to the pump in a closed circuit by a flow line. Connected to the motor via a system shaft is a vehicle system. A controller is connected to a plurality of sensors and a high pressure relief valve that is connected to the flow line between the pump and the motor. Based on information received from the sensors, the controller sets the pump and motor displacements to limit the pressure to a value that will not overspeed the engine and allow the system to automatically provide braking beyond the engine's capability. This may be accomplished through the use of various algorithms.

Abstract: A speed control system for a hydrostatic transmission includes an engine having a drive shaft connected to a hydraulic pump. At least one hydrostatic motor is connected to the pump in a closed circuit by a flow line. Connected to the motor via a system shaft is a vehicle system. A controller is connected to a plurality of sensors and a high pressure relief valve that is connected to the flow line between the pump and the motor. Based on information received from the sensors, the controller sets the pump and motor displacements to limit the pressure to a value that will not overspeed the engine and allow the system to automatically provide braking beyond the engine's capability. This may be accomplished through the use of various algorithms.

Abstract: A speed control system for a hydrostatic transmission includes an engine having a drive shaft connected to a hydraulic pump. At least one hydrostatic motor is connected to the pump in a closed circuit by a flow line. Connected to the motor via a system shaft is a vehicle system. A controller is connected to a plurality of sensors and a proportional high pressure relief valve that is connected to the flow line between the pump and the motor. Based on information received from the sensors, the controller sets the pressure relief valve to limit the pressure to a valve that will not over-speed the engine and allows the demands of the speed control system to be attained. This may be accomplished through the use of various algorithms.