Patent GB-360576-A (GB)
Title: Improvements in, or relating to, brakes for railway vehicles
IPC: B61H9/00
Filed: 1930-09-22
Abstract: 360,576. Fluid-pres-. sure brakes. VACUUM BRAKE CO., Ltd. and STEVENS, W. C. I., 3, Old Queen Street, London. Sept.22, 1930, No. 28265. [Class 103 (i).] In brakes particularly for use on electric, or Diesel locomotives and providing proportional application of vacuum brakes on the train and direct air brakes on the locomotive which proportional application may be cut out, the proportioning device operates a pilot valve, which admits compressed air to a piston which actuates the main air valve for controlling the supply of compressed air to the locomotive brake cylinders. This braking effort on the locomotive may be controlled independently of the vacuum train brakes. Emergency application of the vacuum train brakes gives additional braking effort on the locomotive air brakes by supplying full main reservoir pressure. A diaphragm 20 is controlled by a vacuum chamber 21 and the vacuum train pipe 24, rise of pressure in which on train brake application closes an exhaust valve 27 and raises a pilot valve 30 to admit pressure air from the main reservoir 3, through passage 31, chamber 28, past a double check valve 33 and through a passage 32, to a relay piston 11 which is raised to close exhaust openings 16 and raise a valve 8 to exhaust main reservoir pressure to a chamber 13 and the brake cylinder 15. When the pressure in the chamber 28 balances the pressure in the chamber 22 and the pressure in the chamber 13 balances the pressure below the piston 11 a lap position is obtained with all valves closed. A proportional braking on the train and the locomotive is thus obtained. The locomotive valve 2 may be turned to connect the space below the piston 11 through a pipe 35 to an atmospheric part 42 the locomotive brakes will thus be released independently of the train brakes. The valve 2 may be turned to correct the main reservoir through a reducing valve 5 to a pipe 34 and when the pressure on the double check valve 33 is sufficient to overcome the pressure already existing in the passage 32, this valve is forced down, pressure air is admitted from the pipe 34 and the pressure below the piston 11 is thus increased to give an increased braking effort on the locomotive brakes, the valve is then turned to lap, running or release position. A restricted channel 60 gives a slow application. When the train vacuum brake valve 1 is turned to emergency position, full main reservoir pressure is supplied by passages 6, 34 to the piston 11. In the running position of the valves 1, 2 the pipe 34 is connected to an atmospheric port 41. The train valve 1 also controls the exhauster speed switch which is vented to atmosphere when the train valve is in the release and the locomotive valve in the running position. When the train valve is in the lap and the locomotive valve in the running position the exhauster switch is blanked off. The handle of the train valve is arranged for removal in this position. When the train valve is in emergency position the exhauster stop valve is subjected to full main reservoir pressure. A safety valve may be provided in the brake cylinder pipe and the brake cylinder emergency pressure may blow down as the train comes to rest.