Abstract: A retarder for controlling the speed of a railcar is provided. The retarder includes a brake and a brake actuator that includes a hydraulic piston-cylinder and a spring. One of the piston and the cylinder acts on the brake and the other of the piston and the cylinder acts on one end of the spring. The other end of the spring acts on the brake. In this arrangement, supplying pressurized hydraulic fluid to the piston-cylinder causes both the piston-cylinder and the spring to move the brake towards a closed position in which the brake will apply braking pressure on the wheel of the railcar. The spring resiliently biases the brake into the closed position to maintain a substantially constant braking pressure on the wheel of the railcar as it moves through the retarder.

Abstract: Systems and methods for retarding the speed of a railcar are provided. A supply of pressurized hydraulic fluid is provided to a piston cylinder to actuate the cylinder and thereby move a brake into a closed position in which the brake will apply a predetermined braking pressure to a wheel of the railcar. An accumulator accumulates fluid from the circuit when the wheel forces the brake out of the closed position and supplies accumulated fluid back to the circuit as the brake moves back into the closed position to thereby maintain a substantially constant braking pressure on the wheel as it moves through the retarder.