Empty/load changeover valve for railway car

摘要

An empty/load changeover valve device for a railway car having a proportioning valve via which the car control valve supplies brake cylinder pressure. The proportioning valve comprises a balance piston having equal opposing pressure areas and a combined supply and release check valve, one pressure area of the balance piston being subject to air pressure supplied to the brake cylinder under all conditions of loading. The opposing pressure area of the balance piston is either pressurized or depressurized depending upon the car being in an "empty" or "load" condition, thereby establishing either a nonproportioning or a proportioning mode of brake control. Integrating the release check valve with the supply valve so as to have a smaller effective pressure area, the release check valve can be opened with low force to exhaust brake cylinder pressure during brake release, thereby making possible a reduced size empty/load changeover valve device.