Patent GB-321781-A (GB)
Title: Improvements in or relating to electric traction control systems
IPC: B61L3/14
Filed: 1928-10-03
Abstract: 321,781. English Electric Co., Ltd., and Bremner, F. D. H. Oct. 3, 1928. Systems with motor vehicles having external control; brake signals and alarms; lamp signals: master control systems; controllers, brake devices for.-In an electric traction system with driverless vehicles, the conductor rail is sectioned between stations to provide a power-section p, Fig. 1, a coasting section c with reduced voltage. and a braking section b, section b being divided into sub-sections b<1> b<2>, the former having low voltage and the latter being dead. Any section may have power voltage applied to it to restart a stopped train. The brakes are pneumatically operated but are held off by a solenoid. In operation, the application of power voltage will start the train and accelerate it through section p, low voltage will cause it to coast through section c, and the brakes will be applied on entering section b<1>, but will be taken off and low voltage applied when the speed has dropped to a predetermined value e at which it will run until reaching section b<2> when the brakes will be finally applied to bring the train to rest. An emergency brake is added so as to stop the train upon failure of any device. A train normally consists of a motor coach M, Fig. 2, a trailer T and a driving-trailer D, coaches M, D each having two sets of shoes 1-2, 3-4. A reversing-switch RS is used to connect one set of shoes to the coach controls. When two or more train units are coupled together a control switch CS is also used to determine the control unit. Each unit has control lines L1-7 of which L1 2 connect switches RS, L3 connects the motor controls, L4 is the positive supply, L5, 6 connect switches CS, while L7 is the negative supply. There are also interval control lines L8-13 for each unit, and of these L8, 9 connect to the shoes 3, 4 of coach D, L10, 11 connect the lamps 71, 72, 77, 78, L12 completes the holding-on circuit for the brake solenoids 5, while L13 connects these solenoids. A relay 14 operated only by power voltage closes contacts 15 to energize relays 19a, 29a and complete a circuit from battery 7 through switch 22 to the closing coils 23 of the main motor contactors. A parallel circuit through brake relay 8 closes contacts 9 to energize the brake solenoids 5 from L4 and also the operating coil CO which closes switch 22. To prevent damage 'by power voltage, a resistance 12 may be cut in by relay 13. Solenoids 5 close contacts 10 to complete a holding-on circuit. When the train reaches section c, relay 14 is de-energized and contacts 15 open, to de-energize relay 8 and close coils 23, contacts 17, 30 being held closed by a relay 19 and check relay 29 in series with an axle-driven dynamo 28, the brakes however being held off by the holding-on circuit. Check relay 29 works at a much lower speed than relay 19. If the train reaches section b1 at a speed in excess of e, the brakes are applied until the speed is reduced to e when contacts 18 close and establish a circuit for the brake relay 8 through contacts 16, 30 so that the brakes are again taken off and the train coast at speed e until dead section b2 is reached when the brakes are applied to bring the train to rest. An emergency brake 6 has a time-lag 25 so that it is not applied if the circuit 49 is opened at 24 by operation of the main brakes before the time-lag has actuated. Contacts 26, 27 are provided to break the circuit for solenoid 5 and make the circuit of the emergency brake if the brake pressure is too low. The bain lamps may be used to give an indication that the train devices are in order for starting. The lamp circuits may include contacts 62i for the check relav 29, 64i for the motor coils 23, 66i for the coil CO, 68i for the solenoid 5, 69i for the relay 8 and 70i for the brake pressure. The lamp circuits are also connected to switches RS, CS to indicate their relative positions. Instead of providing automatic motor accelerating- gear on the train, power voltage may be applied to the sections in corresponding steps, with consequent alteration to relay 14.