Patent ID: 7140698

Claim:
A hydraulic control and operating system for a railroad car retarder utilizing a double-acting hydraulic cylinder having a cylinder rod end defined by a cylinder rod attached to a piston, said cylinder rod having an opposite end connected to a car retarder mechanism and an opposite piston end, said cylinder being supplied with operating oil by a motor-driven hydraulic pump drawing operating oil from a reservoir and delivering operating oil to the rod end or the piston end of the cylinder via a control valve, said system comprising: a directional control valve operable to direct operating oil from a supply line from the pump to a selected end of the cylinder and to direct the return of operation oil via a return line to the reservoir; a counterbalance valve between the control valve and each end of the cylinder to hold the position of the cylinder rod at system operating pressure; means for preventing operating pressure spikes and excess pressure excursions from propagating to system components that would be damaged; heat exchange means for controlling the temperature of the operating oil to maintain the oil temperature below a specified maximum operating temperature; means for filtering the operating oil delivered from the reservoir to the pump and returned to the reservoir from the heat exchange means; and means for operating the retarder from a central freight yard control center or at a location of the retarder.