Patent GB-204013-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B60T15/30
Filed: 1923-04-27
Abstract: 204,013. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Farmer, C. C.). Sept. 13, 1922, [Convention date]. Fluid-pressure. - A device applicable both to existing and to new constructions of triple valve comprises an emergency valve adapted first to effect the rapid admission of a limited volume of pressure-fluid to the brake cylinder, and subsequently to effect a temporarily restricted and a finally rapid unrestricted flow of fluid under pressure to the brake cylinder. A cylindrical casing 1 is introduced into the emergency piston chamber of the usual triple valve casing 2, and accommodates a piston 6 which in emergency position engages a seat ring 8. Secured to the piston 6 is an emergency valve 9 and mounted in the piston is a spring check valve 10 having holes 12 in the barrel portion and hole 13 in the face portion. Mounted in the valve chamber 14 is a piston 16 fitted with a depending stem 17 connected with a slight lost motion to the vent valve 18. A spring 20 is interposed between the closed end of the stem 17 and the valve 9. A spring 21 is also interposed between the piston 16 and the vent valve 18. The triple valve casing is provided with the normal piston chamber 22 and piston 24, and with the usual valve chamber 25 provided with slide and graduating valves 27, 28. The usual tail port in the slide valve is plugged, or in new constructions is omitted. Upon a sudden decrease of brake-pipe pressure, the piston 24 moves to the right, the slide valve 27 uncovering a port 29 admitting pressure-fluid from the auxiliary reservoir 26 to the chamber 30. The valve 10 and piston 6 are moved to their seatings, the valve 9 being unseated and the chamber 14 placed in communication with the brake cylinder 32. The piston 16 moving up almost immediately places the brake cylinder in communication with the pressure fluid from the brake pipe 23 through the ports 36 and simultaneously opens the vent valve 18 to atmosphere. When the pressure in the chamber 14 and brake cylinder equalizes with the brake-pipe pressure, the piston 16 seats and the valve 18 closes. While this is taking place, fluid under pressure from the auxiliary reservoir is slowly flowing to the brake cylinder via the port 13. When the brake-cy inder pressure and the tension of the spring 11 are together greater than the reduced auxiliary reservoir pressure acting in the chamber 30, the valve 10 opens and pressure-fluid passes through the ports 12 to the brake cylinder. When the auxiliary reservoir pressure on one side of pistcn 6 equalizes with the brake-cylinder pressure on the other side, the valve 9 is closed by the spring 20 and the piston 6 is restored. In order to ensure that the vent valve 18 will remain open when an emergency reduction in brake-pipe pressure is made after a service application, a piston 39 is fitted as shown. This piston is moved up uncer brake-pipe pressure to vent the latter through the ports 41, and the .stem 40 holds the valve 18 unseated until the brake-pipe pressure has been reduced to substantially atmospheric pressure. When a service application is made, the vent port 42 is connected to the brake cylinder through port 43, cavity 44 in the graduating valve 28, and port 45, to chamber 30 and thence through ports 12. The venting of pressure in the space below the piston 16 outside the seat 15 causes a flow of fluid from the chamber 14 through a port 46 in the piston 16 and port 42 to the brake cylinder so that the higher brake-pipe pressure lifts the piston 16 from its seat.