Patent GB-369919-A (GB)
Title: Improvements in train control apparatus
IPC: B61L3/12
Filed: 1930-11-20
Abstract: 369,919. Automatic train control and signalling systems. RICHARDS, H. W., 8319, Audley Street, Kew Gardens, Long Island, New York, U.S.A. Nov. 20, 1930, No. 35026. [Class 105.]. Relates to a train control and cab signalling system of the inductive type in which permissible-speed limits are automatically imposed in accordance with the state of track occupation ahead whereby the brakes are applied or other signal given if the train speed exceeds such limit. According to the invention the control circuit for the brake application or other signal includes a resistance inserted in accordance with the traffic conditions and a resistance inserted in accordance with the train speed. The train apparatus includes two cores 1, 2 with primary windings 3, 4 fed with alternating current from a generator 17 or with interrupted direct current from a generator 18 and rotary commutator 19. The cores 1, 2 have each a separate secondary winding 6, 7 and one common secondary winding 8 the two fluxes in which normally oppose and balance each other. Co-operating track cores 45, 46 have their windings controlled by polarized relays 50 which are controlled by polarized track relays, the arrangement being such that under clear conditions only the track core winding 47 is open, under caution conditions (second section ahead occupied) only the track core winding 48 is open, while under danger conditions (first section ahead occupied) both windings 47, 48 are open. Under clear conditions therefore there will be an increase of flux in the co-operating cores 1, 45 but not in cores 2, 46 since the core 46 is shaded by its closed winding 48 and the effect will be to increase the current in coil 6 and therebyto pull overthe normally spring-balanced armature 36 of relay G, and to generate a current in common coil 8 (the two fluxes no longer being balanced) and thereby to energize a coil 55 polarizing a double armature 56, 57 to cause its movement to that limb of a relay M which is correspondingly energized by the alternating or interrupted current. The armature 36 of relay G at contact 148 lights a blue zone lamp 12 denoting the presence of the train over a track core and at contact 133 picks up a relay R. The armature of the relay M moves to the left and at contact 80 lights a green lamp 9, at contact 81 energizes a control magnet 21 of the speed limit device, nad at contact 82 energizes a relay B. The permitted speed limit device comprises a relay S having in series therewith a resistance 23, variable with the speed of the train by means of a centrifugal device, and a resistance 20 which is inserted in accordance with the distance travelled after the receipt of a caution track impulse causing the de-energization of the control magnet 21. Should the speed be maintained high after receipt of such caution impulse and concurrent cab signal then the relay S will drop its armature 104 and thereby de-energize the brake valve magnet 16. The mechanism of the speed limit device is shown in Fig. 8. De-energization of the control magnet 21 opens an exhaust valve 283 to vent a cylinder 287 and permit the movement, to the right, of a spring- actuated piston 288 and attached cam plate 296 which actuates a lever 302 with a toothed sector 304 driving a pinion 305 on the arm which varies the resistance 20. An axle-driven pinion 281 by engaging a rack 294 causes the above movement to be proportional to the distance travelled and the cam is of such form that in the first 1000 feet the resistance 20 is not altered so that the driver may control the train during this period. At caution conditions the track inductor action causes the relay Y to be actuated and the relay M to move its armature to the right ; the latter at contact 85 lights the yellow lamp 10 and at contact 86 energizes the relay B while the closure of contact 84 energizes the speed limit control relay 21 only temporarily since the contact 84 leads to armature 96 of relay R which is only temporarily energized over a contact 137 of relay Y during the passage over the track inductor. The train first passes an approach inductor situated 1000 feet from a home inductor which is located at the entrance to a section. With a caution condition therefore, at the approach inductor the speed limit device is released but has no effect and at the home inductor is restored but is immediately released and after 1000 feet of travel begins to impose a gradual reduction of the permissiblespeed limit. A relay X is maintained energized during forward running over forward contacts 110, 111 of a mechanically operated double switch shown in Figs. 9 and 10. The switch comprises a wheel 321 driven from the train axle and carrying a 'pin 329 which engages a dog 327 pivoted on a plate 326 rigid with a cam plate 334 which can rock on an axle 325. In the direction of rotation of the wheel 321 shown the dog 327 rocks idly but on reversal of the train the dog would engage the edge of the plate 326 and rock the plate over and thereafter a second dog 328 would be idly engaged until the train was restored to forward running when this second dog would cause the plate 326 to return to its first position. The cam plate 334 is held in position by a spring detent 340 and is cam-shaped to operate contact springs 336, 335 to close a contact 112 or 157, Figs. 10 and 6. The other face of the wheel 321 has a pin 344 to operate a similar mechanism to close contacts 113 or 158, Fig. 6, but the pin is situated diametrically opposite so that the train must travel 50 feet before both switches are thrown over. A front contact 117 of relay X is included in the circuit to the resistances 20, 23 of the speed limit device and the relay S. On reverse running after a distance of 50 feet the double switch will move both its switches so that relay X will be de-energized and open the above circuit but a high-resistance 162 will be inserted in a circuit to the relay S through the speed-varied resistance 23 ; the resistance 162 requires the reverse speed to be below 15 miles per hour. The movement of armature 64 of relay X from front to back contact momentarily de-energizes relay M and the double armature 56, 57 thereof takes up its neutral position permitting contact 83-87 to light two red lamps 11. At danger conditions on forward running the track inductor action causes both relays G, Y to be actuated to break at contacts 38, 40 the circuit of the relay M the armature 56, 57 of which takes up its neutral position since the two fluxes through the winding 8 though increased remain balanced so that the polarizing coil 55 is not energized. Two red lamps 11 are lit over contact 83-87. Though the contact 86 is now open relay B continues energized over its own contact 176, wire 174 and contact 141-143 since the speed limit device has moved over and reduced the speed limit at the previous caution impulse to close the contact 143, Figs. 8 and 6. If a danger impulse follows directly after a clear impulse the relay B would be de-energized and the brakes applied by the opening of its armature 101 but after the speed limit device has moved over the relay B can be picked up by an emergency pushbutton contact 15 and held over the above stick circuit. By noting the blue zone light 12 the train can be stopped over a home inductor in readiness to receive any signal change. The relay S is maintained energized by a stick circuit over its own contact 122 and is picked up by plugging a connection from a higher voltage source at a station into a socket 181 after the train generator is started, the resistance 183 preventing the train generator supply being used for this purpose. A sealed pushbutton 14 also allows picking up of relay S if the train speed is below that allowed by the speed limit device. The speed is indicated by a voltmeter 13 connected to a rheostat arm 27 adjusted by the centrifugal device. Failure of either winding 6 or 7 would unbalance the armatures of relays G or Y and so open the contacts 39 or 41 to de-energize the relay M.