Patent GB-193981-A (GB)
Title: Improvements in intermittent alternating current induction train control systems
IPC: B61L3/12
Filed: 1921-12-05
Abstract: 193,981. Regan, J. B. Dec. 5, 1921. Track apparatus for stopping trains.- Inductive action between train-carried apparatus and track devices at fixed points always puts the train apparatus into stop condition : if the train may proceed, this condition is momentary, and the train apparatus is, by the inductive action of additional track devices, put either into normal running condition or under the control of a speed-regulator. In one modification, the speed control is omitted. In another, the apparatus is used only to control the speed on curves and other selected parts of the track. The, initial inductive action consists in shunting the magnetic flux from the secondary of a train-carried transformer by means of a mass of iron on the road. The complete apparatus is shown in Fig. 1. The iron circuit of a train-carried transformer J, D is formed with a gap V and a pair of depending poles F<1>. When passing over an iron mass I on the track, the magnetic flux passes through the poles F<1> and the mass I and the secondary current fails. This causes the armatures 65, 66 of a twocoil relay A to fall and break in two places the circuit of a two-coil, three-position relay B. Armatures 67, 68 and 69 take up a middle position and a brake-controlling circuit 29, M is broken at 69. The apparatus may be re-set by a second twocoil, three-position relay C. If a traincarried secondary 62 is not energized by a track primary 62<1>, no alteration takes place and the train is stopped. If the secondary 62 is energized to produce a current in phase with that of the current in coil C, armatures 70, 71 swing to the left and the relay B is re-set: this together with the re-setting of the relay A which takes place immediately the mass I is passed closes a holding circuit for the relay B and safety conditions re-obtain. If the secondary 62 produces a current in opposite phase to that of the coil C, the armatures 70, 71 swing to the right and the relay B is energized to swing its armatures 67, 68, 69 to the right. Armatures 67, 68 thereby close the holding circuit for the relay B but the brakecontrolling circuit 29, M now includes a speedcontrolled switch S and the train is stopped if a limiting speed is exceeded. The apparatus can be re-set manually into the speed-control condition by a switch K which provides a reversed circuit for the coil B<1>. The devices for discriminating between safety, caution and danger conditions comprise a transformer primary 60 on the train, its secondary 60' on the track, a transformer primary 62<1> on the track and its secondary 62 on the train. Contacts 72, 73 are open under danger conditions and the primary 62<1> is not energized. Under caution conditions, contact 74, 75 are in their lower position, the circuit of primary 62<1> is reversed and the current passed from the secondary 62 to the coil C<1> is in opposite phase to that in the coil C. The contacts 72, 73 and 74, 75 may be controlled by magnets H, D in accordance, with the condition of the home and distant semaphores. In the form dealing only with safety and danger conditions, the armature 66 controls the trainstopping circuit, the relays B, C are omitted and a simple relay in the circuit of the secondary 62 is used to re-set the relay A. In the form for controlling the train-speed at curves, the iron mass J<4>, Fig. 7, is placed at the commencement of the section and the transformer parts 63<b>, 64b at the end. Passing over the mass J<4> causes the momentary de-energization of relay R', the circuit of relay R<2> is broken at rand the armature r<11> closes a train-control circuit which includes a speed-responsive device S<3>. When the train reaches the devices 63b, 64b, the relay R<3> is energized and the relay R<2> re-set thereby. Track apparatus actuating signals other than on trains.-The circuit of the track part of a transformer may include a relay whereby a bell is rung at a road crossing whenever a train passes.