Patent GB-239851-A (GB)
Title: Improvements in track-controlled brake apparatus for railway trains
IPC: B61L3/04
Filed: 1925-09-03
Abstract: 239,851. General Railway Signal Co., (Assignees of Leake, R. C.). Sept. 11, 1924, [Convention date]. Fluid-pressure; indicators, applications of.-A cut-out device for track-controlled railway train brake apparatus is rendered effective only by the periodic actuation of a handle by the driver. In the form shown, a manually-operated valve, when placed in the cut-out position, connects the brake pipe venting passage leading from the track-controlled brake application valve to a passage controlled by a further valve actuated by clockwork which must be wound up by the driver periodically to keep the valve closed. The application valve AV comprises a slide-valve 2 with an actuating piston 3 normally subject on both sides to main reservoir pressure through a pipe 6 and port 7, the magnet valve EPV controlled by the track apparatus being normally energized and closed, so that the valve 2 is maintained by a spring 4 in the position shown to establish the main reservoir supply to the driver's valve through the pipe 14. When the valve EPV is de-energized the consequent venting at one side of the piston 3 causes the valve 2 to move to the right to connect the brake pipe through connection 16 and cavity 15 to pipe 17, which with the cut-out valve CO in its normal position is connected by cavity 18, port 19, and pipe 33 to atmosphere. The pipe 33 contains a restricting valve 34, and thus service application of the brakes is effected. At the same time the valve 2 cuts off the main reservoir supply pipe 14 leading to the engineer's valve. The cut-out valve CO comprises a manually-operated slide 20 which, when placed in the cut-out position, re-establishes communication of the main reservoir with the driver's valve through pipes 29, 14, and port 22, should such communication have been cut off by the application valve AV. The slide 20 also disconnects the brake pipe venting pipe 17 from the pipe 33 and connects it to the pipe 30 which is controlled by a normally open valve 67. The valve 67 can be closed to prevent an application of the brakes by the track apparatus by winding-up a olockwork device. This comprises a casing 43 secured to a shaft 41 and having attached thereto one end of a spring 44, the other end of which is fastened to a hollow spindle 36 having a squared bore to receive the squared hub 37 of a toothed wheel 38 screwing on the shaft 41. The wheel 38 is geared to a pinion 52 carrying a gear wheel 51 with which engages the pallets 54 of an escapement controlled by a pendulum 55. Upon turning the shaft 41 by the handle 42 the spring 44 is wound up and the wheel 38 travels to the right on the shaft 41 until the action is stopped by engagement of projections 60, 59 on the wheel and shaft. Reverse movement of the handle and shaft is prevented by a detent 57. Movement of the wheel 38 to the right permits the spring-actuated lever 62 to close the valve 67, which, however, is re-opened if the clockwork is allowed to run down. To indicate when the valve CO is in the cut-out position, the casing of the usual pressure gauge of the brake system is provided with an additional Bourdon tube adapted to be connected through a port 27 in the valve and pipes 28, 29 with the main reservoir. The Bourdon tube actuates a disc 24 with coloured sectors or other means to give the necessary indication. The lever 67 is arranged to sound a whistle W to warn the driver that the valve 67 is about to be opened.