GB377702A - Improvements in or relating to train control systems - Google Patents

Abstract

377,702. Fluid pressure brakes. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, and HUDD, A. E., 947, West Van Buren Street, Chicago, U.S.A. April 22, 1931, Nos. 11971/31, 19143/31, and 641/32. Addition to 351,071, [Group XXX]. [Class 103 (i).] Track apparatus for use in a train control and cab signalling system comprises permanent magnets and electromagnets arranged crosswise thereto and adapted to neutralize the effect of the permanent magnets, as by having their polepieces extended to lie adjacent the permanent magnet poles, or by the magnets crossing at an acute angle, or by the assistance of an auxiliary device which comprises an electromagnet lying parallel with the track-permanent magnets and acting against an auxiliary permanent magnet in a normally closed magnetic circuit to set up an external flux which then neutralizes the effect of the track permanent magnets. The track permanent magnets when effective actuate a magnetic receiver relay R, Fig. 10 (19143/31), to open a venting valve 109 and so initiate a braking and sound a horn 104 if a home or distant signal is not at clear ; at a distant signal the venting valve 109 is shortly afterwards closed bv restoration track permanent magnets located a little way ahead but a partial braking and horn signal continues which can only be cancelled if the train speed is such that a centrifugal valve device S closes its branch pipe to render an acknowledging plunger 120 effective to depress a diaphragm 105 and close the valve 107 which was opened when the spindle 112 of the train pipe venting valve 113 lifted. The centrifugal valve device comprises, as shown in Figs. 1 and 2 (11971/31), a chamber member 30 fixed to a wheel axle and having a spring-pressed weight member 11 provided with a valve 14 to close a port if the speed is below the limit. At a home signal at danger the receiver relay valve 109 is not automatically re-set and a full brake application ensues, the horn only being briefly operated on account of the large direct opening to the train pipe. The relay armature 102 and valve 109 can be re-set by a release plunger 103 actuating a diaphragm and lever device 101 ; this release plunger is only accessible when the train is stopped. Specifications 351,039, 351,072, and 353,502 are referred to.