Patent ID: 8413770
Filing Date: 2013-04-09
Classification: B61K

Abstract:
1. A system for retarding the speed of a railcar, the system comprising: a brake; a hydraulic piston cylinder that causes movement of the brake, the piston cylinder having a rod side and a cylinder side; a pump pumping hydraulic fluid from a reservoir to the piston cylinder; a hydraulic circuit having a first section that conveys hydraulic fluid from the pump to the piston cylinder to move the brake towards a closed position in which the brake will apply a braking pressure on a wheel of the railcar; wherein the circuit further has a second section that returns hydraulic fluid from the piston cylinder to the reservoir; a first hydraulic accumulator that accumulates hydraulic fluid from the first section of the circuit when the wheel forces the brake out of the closed position and supplies accumulated hydraulic fluid back to the circuit when the brake moves back into the closed position to thereby maintain braking pressure on the wheel of the railcar as it moves through the brake; a pressure relief valve coupled to the second section of the circuit, the pressure relief valve being positionable in an open position wherein hydraulic fluid is allowed to flow from one of the rod side and the cylinder side of the piston cylinder to both of the reservoir and the other of the rod side and the cylinder side of the piston cylinder, the pressure relief valve also being positionable in a closed position wherein flow of hydraulic fluid from the one of the rod side and the cylinder side of the piston cylinder to both of the reservoir and the other one of the rod side and cylinder side of the piston cylinder is prevented; and a microprocessor selectively controlling movement of the pressure relief valve into the closed position to and into the open position to thereby quickly control the amount of braking pressure applied by the brake to the wheel of the railcar.