Hydraulic door actuator

A pump for providing pressurized fluid to a pressurized fluid operating device for opening and closing a door comprising

• a pump housing having a pump chamber therein,
• a rotatable pumping element disposed in the pump chamber,
• the housing having a pair of passages extending from the pump chamber to the exterior of the pump housing, the passages being adapted to be connected to pressurized fluid operating device,
• means for driving the pump element in rotation, the pump element being adapted to deliver pressurized fluid to either one of the pair of passages as determined by the sense of rotation of the pump element, the other one of the passages receiving the exhaust flow of pressurized fluid,
• a pair of pressure responsive bypass valves each being connected to a different one of the pair of passages in the pump housing, each of the pair of bypass valves being adapted to bypass pressurized fluid at a predetermined pressure setting, each of the pair of bypass valves when connected to a passage receiving pressurized fluid from the pump cavity being adapted to bypass pressurized fluid to the pump chamber in response to pressure within the passage exceeding the predetermined pressure setting, whereby the predetermined pressure setting can be selected for each of the passages as determined by the sense of rotation of the pump element,
• a shunt valve connected to the pump chamber for shunting the pressurized fluid being directed toward one of the passages back to the pump chamber to reduce the pressure of the pressurized fluid, and
• means responsive to a condition associated with the operation of the pressurized fluid operating device for actuating the shunt valve for shunting the pressurized fluid.