GB213756A - Improvements in and relating to brake apparatus for railway vehicles - Google Patents

Abstract

213,756. Jackson, E. M. March 20, 1923. Fluid-pressure.-Relates tu a valve device fur actuating the compressed-air brakes on a locomotive simultaneously and in equal degree with the vacuum brakes on the train, and refers to the type of valve comprising a valve casing connected to the vacuum train pipe at 9 and to the pressure-fluid brake cylinder at 15, the casing being provided with a spindle 27 carrying members of different areas for operating it by differences of pressure when the vacuum brakes are applied, an exhaust port 14 controlled by a slide valve 26, and a port for supplying fluid under pressure to the locomotive brake cylinder normally closed by a valve 21. According to the invention, the larger pressure member 22 is subject to the vacuum train pipe pressure through the port 9 and to atmospheric pressure through the ports 10, whilst the smaller pressure member 25 is subject to locomotive brake cylinder pressure through the port 15, and to the constant pressure of the main or auxiliary reservoir of the pressure brake system through the ports 12, 13. An intermediate piston 23 is also provided in the construction shown, which prevents leakage of air from the left side of the piston 25 to the atmospheric ports 10. In Fig. 2 the valve 2 is shown installed on the locomotive, the connections to the main reservoir 3, the locomotive brake cylinder 36 through the triple valve 1, and the vacuum train pipe 4 being as shown, so that with the va ve in the normal position shown in Fig. 1, the brake cylinder 36 is open to exhaust through the pipe 37, the exhaust port of the triple valve, the pipe 16, and the ports 15, 14. When the vacuum in the train pipe 4 is reduced to apply the brakes on the train, main reservoir pressure acting on the piston 25 moves the pistons to the right so that the valve 26 first closes the exhaust 14, and a nut 33 on the spindle 27 then opens the valve 21 to admit main reservoir air to the brake cylinder 36, until the pressure on the right hand side of the piston 25 balances the pistons in an intermediate position with the valve 21 and the exhaust port 14 both closed. When the vacuum in the train pipe 4 is restored to release the brakes on the train, atmospheric pressure acting on the right hand side of the piston 22 moves the pistons to the left to exhaust the brake cylinder 36 through the port 14. The valve 2 may be cut out when not required by operating a cock 7 to cut off the reservoir 3 from the pipe 5 and to put the latter to exhaust, when the pistons move to the left to uncover the exhaust 14, and the compressed-air brake functions in the usual way through the compressedair driver's valve. The valve may be used with a straight-air locomotive brake by connecting the pipe 16 to the brake cylinder 3G through a double check valve or a manually operated twoway cock; and it may be used on a vehicle carrying compressed-air braking equipment and a through vacuum train pipe by connecting the pipe 5 to the auxiliary reservoir or the compressed-air train pipe.