Patent GB-266611-A (GB)
Title: Improvements in train control systems
IPC: B61L3/02
Filed: 1925-12-09
Abstract: 266,611. Automatic Telephone Manufacturing Co., Ltd., and Hudd, A. E. Dec. 9, 1925. Fluid-pressure.-In a train control system, the manually-controlled lever for effecting application of the fluid-pressure brakes is also adapted to be controlled automatically by pneumatic means and for this purpose is provided with an arm which engages with the plane surface of a piston 15 which when moving in one direction causes the lever to be operated. The piston 15 allows the lever to be returned by hand only slowly due to the slow escape of fluid through an aperture 63. The automatic operation of the brakes is brought about by short ramps 1 and shoes comprising brushes 5. 6 for cleaning the ramps and a movable brush 3, attached to a carrier 4 movable vertically in ball races. A tapered part of the carrier 4 operates a shalt 42 which raises a ball 43 and a valve 44 when the shoe passes over a ramp. Simultaneously, current flows from a battery connected to the ramp, by a lead 40, contact 37, electromagnet 18. and electrolytic cells 17 to the rails. The electrolytic cells 17 form a large capacity condenser whereby very brief contact at short track ramps is sufficient to control the electromagnet. If the ramp is connected to the positive pole of a battery. corresponding to an " at clear " signal, the armature 19 of the electromagnet moves in an anticlockwise direction and closes a valve 20 by a sliding member 47. Thus air passing from a reservoir 8 by the valve 44 to a pipe 10 is prevented from escaping to atmosphere by the valve 20 and acts on a piston 8<a> on the end of the shaft 42 to close the valve 44 when the shoe leaves the ramp. If the ramp is uncharged, the valve 44 is opened as above. but the air escapes from the reservoir 8 through the valve 20 and a diaphragm 12 falls, opening a valve 13 which allows air from the main air pipe 50 to operate the piston 15 and the driver's valve. If the ramp is negatively charged, the electromagnet 18 swings the armature 19 in a clockwise direction which also closes the valve 20 by means of the sliding member 47, and a projection 52 on the armature 19 moves a catch 26<1> and release a pivoted member 25 to open a valve 54. The member 25 engages the projection 52 on the armature 19 when the armature is restored to the position shown and before the member 26<1> is restored to normal position, so that the armature 19 is prevented from again moving in a clockwise direction due to negatively-charged ramps. A weighted sector 24, carried on a bracket 57 connected to an extension of the catch 26', falls when the catch is moved and engages a roller 27 of a timing mechanism to prevent the catch 26<1> from returning until the roller 27 has raised the sector sufficiently. The opening of the valve 54 admits air to a whistle 23 and a jet 19<a> which operates a turbine 20<a> driving the timing mechanism. If the speed of the train is reduced so that before the next ramp is reached the sector 24 has been raised to allow the catch 26<1> to be returned by air pressing on the diaphragm 26, the member 25 will be restored by the catch 26 and the valve 54 is thereby closed. If another negatively-charged ramp is reached before the valve 54 is thus closed, the valve 20 cannot be closed as the armature 19 is locked in position, und the valve 44 will be locked' open as the pressure to restore the piston 8<a> escapes by the valve 20 and the driver's valve will thus be operated by the piston 15. To avoid excessive current drain due to the train coming to rest with a shoe on a ramp, a high-resistance electromagnet 36 is provided which on current being received for a longer time than usual will open the contacts 37, thereby inserting a resistance 38 in series with the electromagnet 18. Simultaneously a valve 51 is closed, permitting the reservoir to fall through a restricted orifice 35 connected to the pipe 50. To allow for operation for both direction of running, a shoe is provided on each side and pipes 9, 10 are taken through two-way cocks and a connected wire 40 through a twoway switch. The two-way cocks and two-way switch are attached to the reverse lever of the locomotive. A cancelling device for closing the valve 20 and resetting the brakes comprises a pawl 30 which is brought into engagement with a projection 31 on the armature 19 when the pressure behind a diaphragm 32 falls on the exhaustion of the reservoir on an automatic brake application. On moving the cancelling lever, which controls an arm 34, in a clockwise' direction, the armature 19 is moved to close the valve 20. The reservoir 8 is then recharged and the valves 13, 44 closed. Specification 266,485, [Class 105, Railway signals &c.]. is referred to.