Patent GB-229248-A (GB)
Title: Improvements relating to train control apparatus
IPC: B61L3/00
Filed: 1924-07-31
Abstract: 229,248. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Farmer, C. C., and Thomas, T. H.). Feb. 15, 1924, [Convention date]. Track apparatus for stopping trains.-In apparatus for controlling the speed of a train automatically in accordance with a signal indication, the action of the mechanism for applying the brake automatically if the speed of the train exceeds that corresponding to a signal indication which imposes a lower speed limit is arranged to be superseded if a brake application, sufficient to reduce the speed of the train to the lower speed is effected through the driver's valve, the pressure fluid released from the train pipe serving to prevent the action of the automatic mechanism only if a predetermined reduction in train pipe pressure is made within a predetermined time. The application valve of the automatic mechanism, which is subject to main reservoir pressure, is controlled by a pilot valve subject only to feed valve pressure. When the low speed limit is imposed, an acknowledging valve must also be actuated by the driver within a predetermined time in order to prevent an automatic brake application; the automatic application is effected in two stages at speeds below the medium speed limit; and after an automatic brake application, release of the brakes through the driver's valve is delayed. The apparatus comprises a driver's valve 1, an acknowledging valve 2, a governor valve unit 3, comprising governor controlled valves 13-17, change speed valves 20, 24 controlled by pistons 18, 22, diaphragm controlled timing valves 34, and 39, 41, and control magnets 43, 46, and an application slide valve 69, Fig. 2, operated by a piston 67 controlled by a pilot slide valve 73 operated by a piston 71. With the driver's valve in the running position shown, the train pipe 108 is charged from the main reservoir 109 through the passage 110, application valve chamber 70, passage 111 and feed valve 113, the chamber 97 of the driver's valve being charged to the full main reservoir pressure. The train pipe charges a chamber 92 below a piston 87 controlling a discharge valve 91, a chamber 58 above a diaphragm 56, a. reservoir 115 through passages 117, 118 in the driver's valve and a passage 116 which also leads to a chamber 57 below the diaphragm 56, and an equalizing-reservoir 90 and a chamber 88 above the piston 87, through a cavity 123 in the driver's valve, a passage 124, a cavity 125 in the slide valve 69, and a passage 89. Air from the main reservoir is also supplied through a feed valve 126 and passage 127 to the chamber 74 of the pilot slide valve 73, to the chamber 86 of a two stage reduction control slide valve 85, and to the chamber 105 of the acknowledging valve 2. When the train runs under a high-speed signal indication, the magnet 43 is energized, and the magnet 46 de-energized. The valve 45 being thereby unseated, the chamber 19 of the piston 18 is supplied with pressure fluid from the passage 127 bv a passage 128, and as the chamber 21 is also charged from the passage 127, the piston 18 is held in the position shown by a spring 129, in which the chamber 21 communicates by a passage 130 with a reservoir 131 and a chamber 32 below a diaphragm 31, which are accordingly charged. The valve 34 is thereby moved to cut off a passage 132, leading from the piston chamber 72 of the pilot valve, Fig. 2, and past an open valve 64, from a passage 133 leading from the chamber 84 of the two stage reduction control valve to the medium speed governor valve 13, Fig. 1, so that the opening of this valve will not effect a brake application. The chamber 21 is also connected by a passage 135 in the slide valve and a passage 136, with a reservoir 134 and a chamber 37 above a diaphragm 36, and the valve 39 being thereby closed and the valve 41 opened, pressure fluid passes from the passage 127 by a passage 137 to the chamber 23 of the piston 22, so that the piston is held in the position shown by a spring 138 and a cavity 141 in the slide valve 24 connects a reservoir 139 to atmosphere through a passage 140.. If the train is running above the medium speed limit, the passage 133 being connected to atmosphere through the valve 13, the piston 83 of the two-stage reduction control valve is raised as shown by pressure in the chamber 86, in which the slide valve 85 connects passages 143, 144 leading to reduction reservoirs 54, 55. These reservoirs then act as a single reservoir, and the two-stage reduction is cut out of action. The passage 144 is normally connected to atmosphere through a passage 150 in the slide valve 69 and a port 149. If the high speed governor valve 15, connected to the passage 132, is opened by excessive speed, the chamber 72 of the pilot valve is vented, and the piston 71 moves outwardly so that the slide valve 73 cuts off the chamber 68 of the application valve from the chamber 70 and vents it to atmosphere, at 148. The piston 67 then moves to application position, in which the passage 89, leading to the equalizing-reservoir 90 and to the chamber 88 of the discharge valve, is connected by the passage 150 in the slide valve to the passage 144 leading to the reservoirs 54, 55, a restricted port 151 ensuring gradual pressure reduction. The piston 87 is now raised bv train pipe pressure to open the valve 91, and the train pipe is vented to a passage 152 leading to a chamber 76 above a piston 75, which is thereby depressed. The train pipe is then vented through a restricted port 157 in a passage 153, and also through a passage 154 and a restricted outlet 156, and a restricted port 159 in a passage 158 in' the slide valve 69 and the port 149. The ports 157, 156, 159 ensure a gradual reduction in train pipe pressure, and the valve 91 closes only when a service application has been effected. Thereafter, as soon as the valve 15 closes, the driver can release the brakes, but since the passage 132 has been connected to atmosphere through a port 161 in the slide valve 69, a passage 160 and a valve 103, Fig. 1, he must first move his handle to lap position to vent a normally charged chamber 102, so that the valve 103 may close. Pressure in the chamber 72 of the pilot valve can then build up through a port 163 in the piston 71 until the piston returns to release position in which the chambers 68, 70 of the application valve are again connected, so that this valve also returns to release position. The driver may then release the brakes in the usual way. If, when a speed limit is imposed, the driver makes a full service application of the brakes within a predetermined time, the action of the automatic apparatus is cut out as follows. In the application position of the driver's valve, the passage 116 is connected to the passage 120, so that fluid is vented from the reservoir 115 and the chamber 57 below the diaphragm 56 to a reduction reservoir 119. The passage 124 is also connected to exhaust to vent the equalizing- reservoir 90 and the chamber 88. The train pipe is therefore vented as above described through the valve 91, passage 152, and restricted ports 157, 156, and also, the valve 69 being in release position, through a cavity 166 therein, a passage 167 and non-return valve 168, to a chamber 63 below a diaphragm 62, a timing-reservoir T.R. 2 and a valve chamber 61, and thence, the diaphragm 57 being depressed, past an open valve 59 to a restricted exhaust port 170. The diaphragm 63 is now raised by the pressure below it to open the valve 65 and close the valve 64. The part of the passage 132 leading from the chamber 72 of the pilot valve is therefore cut off from the part leading through the valve 34, Fig. 1, to the passage 133 connected to the medium speed governor valve 13. When train pipe pressure has been reduced to a value slightly below that in the chamber 57, the diaphragm 56 will rise to close the valve 59 to prevent further venting of the reservoir T.R. 2 and the chamber 63, so that. the valve 64 is held closed. If, however, train pipe pressure is not sufficiently reduced, the valve 59 remains open, and when the reservoir T.R. 2 has completely vented, the valve 64 opens to connect the parts of the passage 132 through the passage 133 to the valve 13, so that if the medium speed is exceeded an automatic application follows. The delay in venting the reservoir T.R. 2 allows the driver to make his application in two stages if he wishes. Under the medium speed indication the magnet 43 is de-energized and the magnet 46 energ.ized. The exhaust valve 44 being thereby opened, the chamber 19 is vented through the passage 128, so that the slide valve 20 moves to the right. The valve 48 being opened, the passage 127 now feeds the reservoir 134 and the chamber 37 through a passage 172, cavity 171 in the slide valve 20, and passage 136, but the reservoir 131 and chamber 32 are connected 'by passage 130, cavity 173, and passage 174 to a blow down valve 16. Accordingly, in a time determined by the speed of the train and the consequent degree of opening of the valve 16, the diaphragm 31 allows the valve 34 to open to connect the passages 132, 133. If the speed of the train remains above the medium speed limit, the application valves will then be operated as already described to give an automatic brake application, and a full service reduction in train pipe pressure will be superadded to any already made by the driver, if his reduction has not been sufficient to close the valve 59 and keep the valve 64 seated. In the event of an automatic brake application, release by the driver is delayed until the passage 132 has been recharged through port 163 in piston 71 and a restricted port 175, and the application valves have returned to release position. As soon as the speed of the train falls below the medium speed limit, the pipe 133 is cut off from the atmosphere, so that the pressure in the chambers 84, 86 of the two stage reduction control valve equalise through a restricted port 177