Patent GB-190504543-A (GB)
Title: Improvements in Apparatus for Working Pneumatic Railway Brakes.
Inventor: MCDERMID WILLIAM FRANCIS
Filed: 1905-03-04
Granted: 1905-11-16
Abstract: 4543. McDermid, W. F. March 4. Brakes.- To provide means for applying the pneumatic -pressure brakes of a detached vehicle several times, a hand-control valve is fitted in connexion with the usual triple valve, and incidentally combines the functions of the release valve and of the cut-out cock for disconnecting the reservoir of any vehicle from the train - p i p e. The control valve comprises a plug or disk which can be turned within a casing to connect various ports and passages as required, the 'on,' 'off,' and 'cut-out' positions of the handle being defined by stops, and a special operation being necessary to move the handle to the ' cut-out' position. Figs. 5 and 6 show transverse sections of one form of the valve which is used in connexion with a supplementary reservoir, the latter being provided so that the brakes of a detached vehicle can be applied and released a greater number of times. Fig. 8 shows a development of the plug, and Fig. 7 of the inside of the casing. The port a in the casing leads to the train-pipe, g to the supplementary reservoir, c to the brake cylinder through a non-return valve c<1>, b to the triple valve, and d to atmosphere. The large end of the casing is connected to the principal reservoir as shown in Fig. 5. The port a opens into a passage formed by grooves a' running around the plug and the inside of the casing. The plug is hollow, as indicated by dotted lines in Fig. 8, the hollow being connected to the main reservoir through a passage e and non-return valve e<1>. In all positions of the valve, when used only for control, the train-pipe and triple valve are in communication through the port a, passages a', a<2>, elongated passage a<3> and the port b. In the neutral position of the valve, the line x on the plug is midway between the lines y, z on the casing, and air can pass from the main reservoir to the supplementary reservoir through the passage e. the valve e<1>, the hollow in the plug, and the ports g<1>, g. To apply the brake, the plug is turned so that its line x coincides with the line y on the casing. Air then passes from the trainpipe to the brake cylinder through the passages a, a<1>, a<2>, a<3>, c and the valve c', and from the trainpipe to atmosphere through the passages a, a<1>, a<4>, d, so that the triple valve is actuated, and the two reservoirs are connected through ports g, g<2>. To release the brake, the line x is made to coincide with the line z. Air then flows from the supplementary reservoir to the train-pipe through the ports g, g<1>, the hollow in the plug, and the ports e<2>, a, and from the main reservoir to the train-pipe through the passage e, valve e<1>, hollow plug, and ports e<2>, a. When the pressures are equalized in the train-pipe and main reservoir, air continues to flow from the latter through the passages e, f, d to atmosphere, so that the reservoir pressure is reduced below the train-pipe pressure and the triple valve is operated. To use the valve as a cut-out cock, the line x is made to coincide with the line w ; the main reservoir is then exhausted to atmosphere through the passages e<3>, d, the supplementary reservoir is exhausted through the passages g, hand the main reservoir, and all the other connexions are closed. The parts may be returned to the neutral position by springs. A valve for use when a supplementary reservoir is not employed is also described, the passages g. g<1>, g<2>, h being dispensed with. According to the Provisional Specification, when the valve is moved into the position for applying the brakes, the train-pipe may vent into the atmosphere only.