Brake Cylinder Limiting Valve

摘要

A brake cylinder limiting valve having a first portion that determines actual brake cylinder pressure and a second portion that determines intended brake cylinder pressure based on brake pipe pressure reduction. The two portions are combined so that brake cylinder pressure will be vented if the actual brake cylinder pressure exceeds intended brake cylinder pressure by a predetermined threshold amount, which is preferably two and one-half times the brake pipe pressure reduction. An exhaust cut-off valve may be used to prevent venting of the brake cylinder pressure if it falls below a predetermined value.

主权项

1. A brake cylinder limiting valve, comprising:
a first portion for interconnection to a source of brake cylinder pressure and having a seat that is moveable between a closed position where the source of brake cylinder pressure is in closed communication with an exhaust and an open position where the source of brake cylinder pressure is in open communication with the exhaust; a second portion for interconnection to a source of brake pipe pressure and a source of emergency reservoir pressure that provides a force biasing the seat into the closed position when brake pipe pressure is less than emergency reservoir pressure; and wherein the force biasing the seat into the closed position is overcome when the brake cylinder pressure exceeds the brake pipe pressure by more than a threshold ratio.