Patent GB-190415466-A (GB)
Title: Improvements in Air Brake Systems and Valves therefor.
Filed: 1904-07-11
Granted: 1905-05-11
Abstract: 15,466. British Thomson-Houston Co., [General Electric Co.]. July 11. Brakes, valves for. In order to ensure that, after an application of the brakes, the brakes on the rear cars of the train shall be released before those on the engine, thus avoiding excessive strain on the draw-bar due to premature starting of the engine, the driver's valve is designed to operate in two positions of release. In the first position, the triple valves on the cars, and in the second those on the engine, are actuated to effect the release. Fig. 4 shows the ports in the rotary valve V, and Fig. 5 those in the valve seat. The port l<1> in the seat communicates through the chamber 18, Fig. 2, with the train-pipe, and the port r' through the chamber 17 with the main-reservoir pipe r. The port a<1> is connected to the exhaust port a, and the ports e', e<11> communicate with the chamber 21 leading through a passage e to the equalizing - reservoir. On reducing the pressure in this reservoir, the train-pipe is connected through the port 24 to the exhaust pipe 25. Air pressure is supplied from the main reservoir to the train-pipe, as usual, through a reducing-valve 20, which consists of a slide valve 26, mounted in a chamber 30 connected by a passage 19, Fig. 3, to a port s<1> in the valve seat. The slide valve is carried by a piston 29 held in position by a spring 28. The lift valve 32 is pressed downwards by a spring 34 and carries a pin extending into engagement with a diaphragm 35 normally held downwards by pressure in the train-pipe against a spring 36. During the application of the brakes, when the train-pipe pressure is lowered, the diaphragm 35 is pressed upwards and raises the valve 32, thus connecting the chamber 31 to the train-pipe. If, now, the reservoir pressure be admitted above the piston 29 through the valve port s<1> and passage 19, the piston will be depressed and will carry with it the valve 26, which will open the port 27 and allow the train-pipe to be charged until the pressure in the chamber 31 increases sufficiently to push the piston upwards and close the port 27. While the brakes of the train are being thus taken off, the locomotive triple valve is disconnected from the train-pipe by means of the valve 47, Fig. 3, thus preventing the release of the brakes on the locomotive. The driver's valve seat has a port f, Fig. 5, which is connected to a chamber 38 by passage 37. The chamber 41 is connected through a port 46 to the train-pipe, and, in the position of the valve shown in Fig. 3, is also connected through a passage 42 to a pipe t leading to the triple valve on the locomotive. A piston 40 carries a slide valve 44, which cuts off connection between the triple valve and the trainpipe when the piston moves to the right, and connects the pipe t through the passage 42 and port 43 to a small exhaust port 45. When the brakes on the train are released by admitting air into the train-pipe, the chamber 38 is connected by the port f through ports 14, a' to exhaust; the pressure of the train-pipe on the left side of the piston 40 then moves it to the right, cutting off the connection between the train-pipe and the triple valve t and connecting the locomotive triple valve e through ports 43, 45 to the atmosphere. The valve V has six positions, shown by dotted lines 1 to 6, Fig. 5. Position 1 is the emergency application, the port l<1> being connected directly through ports in the rotary valve to exhaust a. For ordinary applications, the pressure in the equalizing-reservoir is reduced at position 2, and, on moving the valve to position 3, the train-pipe pressure is reduced to that of the equalizer. In position 4 the brakes on the train are released as described above, and the chamber 38 is opened to exhaust to prevent the release of the locomotive brakes. In position 5 the brakes on the locomotive are released by equalizing the pressure on both sides of the piston 40, causing it to move to the left and admit trainpipe pressure to the triple valve on the locomotive. If any of the triple valves should stick, the handle is moved to position 6, connecting the reservoir directly to the train-pipe.