Patent ID: 6314729
Filing Date: 2001-11-13
Classification: F01P

Abstract:
A hydraulic fan drive system, comprising, a fan coupled to a fan hydraulic motor, a single hydraulic purnp connected to the fan hydraulic motor and having a pressure outlet flow capability greater than the fluid flow required to operate the fan motor at the normal operating speed, a pressure reduction valve connected to a pressure flow outlet line of the pump upstream of the fan hydraulic motor, an electronic controller operatively connected to the pressure reduction valve to control the fluid pressure therethrough, a plurality of temperature sensitive bodies associated with the system, a signal emitting sensor associated with at least some of the bodies and connected to the controller to transmit an electronic signal to the controller relative to the temperature of the body from which it extends, whereby the controller can adjust the fluid pressure to the fan motor through the pressure reduction valve to increase or decrease the speed of the fan to accommodate the temperature needs of the bodies which the controller determines; the pressure reduction valve includes a pressure reducing valve and a solenoid-operated proportional relief valve located between the controller and the pressure reducing valve and operatively connected to each to permit signals emitted from the controller to influence the pressure reducing valve to alter its outlet pressure to the fan hydraulic motor.