APPARATUS AND METHOD FOR PNEUMATICALLY CONTROLLED GRADUATED BRAKE PRESSURE RELEASE FOR FREIGHT TRAIN BRAKE SYSTEM

摘要

A graduated release valve for freight brake control is provided for a railca r having a pneumatic control valve, emergency and auxiliary reservoirs each normally charged with pressurized fluid from a brake pipe and a fluid pressure activated brake cylinder device for applying the brakes on the railcar. A selectively operable graduated release valve can include a metering valve an d a changeover valve which selectively interposes the metering valve to exhaust brake cylinder pressure in a graduated manner responsive to brake pipe pressure. Alternatively, the changeover valve can isolate the metering valve and direct the pneumatic control valve to exhaust brake cylinder pressure in a conventional manner. The changeover valve can be operated responsive to the pressure in an air pipe supplied with pressurized fluid from a remote source. An auxiliary reservoir charging check valve interposed between the auxiliary reservoir and the brake pipe prevents the pneumatic control valve from going to release by connecting the brake pipe to the auxiliary reservoir.