Emergency brake valve device for propogating an emergency brake application

Abstract From the Canadian patent

An emergency brake valve device, especially for rapid transit railway vehicles, in which a vent valve for propogating transmission of an emergency rate reduction of brake pipe pressure is opened by direct engagement thereof by a brake pipe pressure reduction rate sensitive piston subjected unrestrictedly to brake pipe pressure on one side and to control brake pipe pressure communicated to the opposite side via a choke. A magnet valve device connected to brake pipe pressure on the one side of the rate sensitive piston provides for electrically initiating reduction of the brake pipe at an emergency rate and, consequently, an emergency brake application.