Patent GB-563966-A (GB)
Title: Improvements relating to automatic train control systems
IPC: B61L3/12
Filed: 1943-03-03
Abstract: 563,966. Track apparatus; actuating signals on trains. LOMAS, P., and BOUND, A. F. March 3, 1943, No. 3481. [Class 105] The invention relates to a cab-signalling system in which an armature of a magnetic receiver on the locomotive is deflected and returned by permanent and electromagnets on the track to control pneumatic means having a quick-action vented chamber by which an audible signal of predetermined short duration is given when the receiver armature is only momentarily deflected and a slow-action vented chamber by which an audible signal of a different kind is given when the receiver armature is deflected but not returned, the sounding of the first signal being impossible in this condition. According to the invention the venting of the pneumatic means is effected by an electrically controlled pneumatic valve and the arrangement is such that momentary deflection of the receiver armature acts as a trigger release for the pneumatic valve to start a series of operations including the rapid venting and timed restoration of the quick-action chamber and the sounding of the audible signal of predetermined short duration whereas deflection of the receiver armature without early restoration allows the pneumatic valve to remain open, whereby the slow-action chamber is vented to bring into operation the audible signal of different kind, the sounding of the first signal being impossible meanwhile. The audible signal of different kind continues until the device performs an acknowledging action ; this acknowledging action, in co-operation with a member actuated by the quick-action chamber, operates a visual indicator which remains set until the next track magnets are passed. Fig. 1 shows an arrangement operating in conjunction with a vacuum braking system. At a clear track signal the receiver-magnet armature a is briefly operated and returned ; the first action opens a contact f<1>-h, whereby a valve magnet 3 is de-energized to open a venting port m, whereby atmosphere is admitted to the underside of a diaphragm 23 of a quickacting vacuum chamber A ; a contact f<1>-70 is also closed to energize a slow release relay 71. The return of the armature a energizes the valve magnet 3 over contact 73-72 closed by the arm 75 of the slow release relay 71 and the valve magnet 3 thereafter continues energized over its own contact l. The quick-acting vacuum chamber A has a diaphragm 23 normally biassed by a spring 24 to close a large venting port 21, but when the port m is opened to the atmosphere the diaphragm is lifted to open the large port 21 and pressure equalization is speedily effected above the diaphragm through ball valve 26 whereupon the diaphragm 23 descends to close the large port 21. With atmospheric pressure in chamber A, a diaphragm 27 is displaced by a spring 29 to move a rod 28 to the left whereby a slide 35 if not already at the left is also moved to the left through an inclined-ring clutch 36. This slide carries contact fingers 54, 56 engaging with fixed contact pieces 53, 55 and with a contact plate 33 mounted on the rod 28. A bell 59 accordingly rings as its winding 58 is energized from generator g, over receiver-magnet armature contact f<1>-h, valve magnet contact l, contact pieces and fingers 53, 54, 33, 56, 55. Meanwhile, since the re-closure of port. m, vacuum is being restored in chamber A from a reservoir u through space s of a slow vacuum chamber B, restricted opening 12, passage 13 and passage 18a, it being noted that a diaphragm 19 descended when a sufficient vacuum on the underside had been restored through a restricted opening 20a. When the vacuum in chamber A is restored, the diaphragm 27 moves to the right to retract the contact plate 33 from the contact fingers 54, 56 to open the bell circuit ; the inclined-ring clutch 36 is ineffective in this direction so that the slide 35 remains at the left. Thus the bell rings for the period determined by the time of restoration of vacuum in the chamber A, e.g. one second, and it will be noted that ringing does not commence until the receiver-magnet armature a is returned to close contact f<1>-h. At a caution signal the receiver-magnet armature a is operated but not returned. In this case the vacuum is not restored in chamber A and air passes therefrom through a restricted opening p into the slow vacuum chamber B to move a diaphragm r to the right so as to open a valve y and sound a horn 11 by air entering therethrough. A brake valve 16 will also be gradually actuated by air entering through a restricted opening 20 in the now-raised diaphragm 19. To cancel this signal and braking, the driver operates an acknowledgment push 47 so closing a circuit from generator g, over contact 49-50, contact fingers 63, 64 bridged by a contact piece 34 mounted on the rod 28, to a winding 66, whereby the receiver-magnet armature is returned to close its contact f<1>-h. This action energizes the valve magnet 3 to restore the vacuum in chamber A (and chamber B) as before described. Operation of the push also by its arm 51 pushes back the slide 35 to open the point 53, 54, 56, 55 in the bell circuit. An inclined slot in the slide engages a pin on a disc (not shown), whereby coloured sectors on the disc are brought into register with apertures in a masking plate so as to give a visual indication of the cancellation action at the passage of a caution signal. The slow release relay 71 with contacts 72, 73 may be substituted by using- make-before-break contacts on the armature a, Fig. 4 (not shown). Specifications 353,502 and 477,319 are referred to.