Patent GB-234884-A (GB)
Title: Improvements in train control apparatus
IPC: B61L3/10
Filed: 1924-02-29
Abstract: 234,884. Haddan, R., (Regan, J. B.). Feb. 29, 1924. Electrical systems, automatic and non-automatic; track apparatus for stopping trains. - In an automatic electrical train-control system involving cooperation between traincarried and track apparatus, the circuit arrangements are such that the train may pass a track device under " caution " condition without automatic application of the brake provided the speed is previously reduced below a predetermined limit, but automatic application of the brakes occurs if the speed has not been so reduced, or if the track device is passed under "danger" condition. Hand-operated, switches are also provided whereby, after an automatic brake-application has been initiated the driver may resume control to prevent complete stoppage of the train and proceed at or below predetermined low speedlimits. The speed-control arrangement is also such that a maximum speed limit is imposed under " clear " conditions. The system described involves the use of electrically conductive ramps, and the arrangement is such that a fault in a ramp circuit sets the corresponding track signal at " danger," and defective, operation of a signal is indicated by a ramp-produced effect. A turn-out from the main track is described with arrangements whereby, when the switch points are operated to run the train into the siding, a restrictive running is produced. Control is effected by a normally-energized magnet 1, deenergization of which causes application of the brake by venting the train-pipe 6 through an audible warning device 9. Magnet 1 is normally energized from train-carried battery 13 through conductors 17, 18, 19, 20, contact 21, conductor 23, governor controlled switch member 25 bridging contacts 24, 26, and conductor 27. Contact is broken at 24, 26 if a predetermined maximum speed is exceeded, irrespective of track conditions, so de-energizing magnet 1. Contact 21 is one of a number of contacts 33, 44, 87, 21, 89 of a three-position polarized relay 30, normally energized to hold the contacts to the left, Fig. 1. Relay 30 is normally energized from battery 13 through contact 33, conductor 34, switch member 37 carried by a vertically movable shoe 29 and normally bridging contacts 35, 36, conductor 38, relay 30, conductor 39, contacts 40, 41 normally bridged by shoe-carried member 42, conductor 43, contact 44 and conductor 45. Shoe 29 is raised by engagement with a ramp rail 28 fixed beside the track, and contact is broken at 35, 41, contacts 36, 68, and 40, 69 being then bridged bv the members 37, 42 respectively. Connection is thus broken between battery 13 and relay 30, and connection established between a track battery 46 and relay 30 through one contact 48 of a pole-changer, conductor 53, ramp 28, shoe 29, conductor 67, contacts 68, 36, relay 30, contacts 40, 69, conductor 70 to engine frame, through one of the track rails 52, conductors 66, 63, contact 50, a. relay 60, and contact 47 of the pole-changer. If " clear " conditions exist, the pole-changer is in the position shown and battery 46 energizes relay 30 to hold its contacts in the normal position shown. Magnet 1 is thus maintained energized. If " caution " conditions exist, the battery connection is reversed at the pole-changer contacts 47, 48 and contacts of relay 30 are moved to the extreme right. Circuit of magnet 1 is broken at contact 21 and the brakes applied. Contacts 33, 44 prepare a circuit by which the caution condition of relay 30 is maintained from battery 13 when the shoe leaves the ramp. If "danger" conditions exist, contact 50 is open, ramp 28 is dead, and relay 30 is deenergized, its contacts assuming the mid position. In this case also circuit of magnet 1 is broken at contact 21. After brake-application has been initiated at a " caution " ramp, and when speed has been reduced until member 25 bridges contacts 26, 84 corresponding with a medium speed limit, the driver can prevent complete stoppage and proceed at reduced speed by closure of contacts 77, 78 arranged so that they can be closed momentarily by mechanical impulse applied to a push-button 79. A hold-on circuit is thus closed through a coil 76 and contact 84, maintaining contacts 77, 78 closed. Contact 78 closes a.n energizing circuit through magnet 1 over contacts 26, 84, 78, conductor 86, contact 87 (in extreme right position), and conductors 85, 20. To allow the driver to pass a " caution " ramp without automatic application of the brake. and without the necessity for manually operating switches 77, 78, provided that speed has previously been reduced sufficiently to bridge contacts 84, 26, a circuit is provided in shunt with contact 77 whereby closure at contact 84 energizes coil 76 over conductors 83, 90, contact 89 in normal position shown, and conductor 88. Contacts, 77 and 78 are thus lifted and function to maintain magnet 1 energized irrespective of subsequent opening of relay contacts 21, 89 at the ramp. Handoperable switches 93, 94 are also provided whereby, after brake-application has been initiated at a " danger " ramp, complete stoppage may be avoided, and progress continued at a low speed determined by a governor-closed contact 100. Contact 93 closes a hold-on circuit through coil 92 over contacts 26, 100, maintaining switchmembers 93, 94 raised, and contact 94 closes an energizing circuit for magnet 1 over contacts 26, 100 and relay contact 87 in mid-position. Indicating lamps 104, 105, 107 are provided, the circuits of which are respectively broken at contacts 24, 84, 100 when the corresponding maximum, medium, and low speeds are exceeded. The track rails 52 are in insulated sections provided with track relays 110 and track batteries 112. The partial circuit to the ramp 28 is controlled by home and distant relays 51, 49 which also control the signal 109, relay 51 representing the condition of the block immediately in advance of the signal, and relay 49 of the block second in advance. Relay 51 is controlled by contact 113 of track relay 110. Relay 49 is controlled by contact 123 of home relay 51 and by the circuit controller of the signal in advance. Contact 50 ensures dead condition of ramp 28 when the section in advance is occupied. Contacts 47, 48 effect reversal of current to ramp 28 from battery 46 when the second section in advance is occupied. Signal 109 is controlled by contact 125 of relay 60, and contact 129 of relay 49, the signal going to " danger " when contact 125 is open, and to " caution when contact 129 is open. A detecting circuit is provided from battery 46 through relay 60 over contact 50, conductor 132, ramp 28, and conductor 53, so that relay 60 is de-energized and contact 125 opened, putting signal 109 to " danger," when the ramp detecting circuit is broken. A contact 65 operated in conjunction with signal 109 is provided in the ramp partial circuit and keeps this circuit closed when the signal indicates " clear " or " caution," but broken when it indicates " stop." In conjunction with a track switch 135 for a siding 134 contacts 118, 136 are provided, the former normally included in and closing the circuit of relav 51, so that operation of the switch 135 de-energizes both relays 51, 49. At the same time a contact 136 closes an energizing circuit through relay 60, maintaining contact 125 closed. Contact 129 is opened by the de-energization of relay 49, so that signal 109 indicates " caution." Two modified circuit arrangements of the system are described.