Patent GB-191213125-A (GB)
Title: Improvements in Railway Signalling.
Inventor: TARRANT REUBEN WILLIAM
IPC: B61L23/12
Filed: 1912-06-04
Granted: 1913-05-29
Abstract: 13,125. Tarrant, R. W., and Sykes, J. C. June 4. Combined electrical and mechanical systems, non- automatic; signalling-instruments. -Apparatus is provided whereby existing block-telegraph systems may be converted into lock-and-block systems, although the apparatus may, as a whole, constitute a complete and self-contained installation. A singleline section A-B is shown with a starting-signal 12 operated by a lever 14, and a home-signal 13 at the exit end of the section operated by a lever 49. The lever 14 is locked in the " danger " position, as shown, by the engagement of a magneticallycontrolled bolt 19 engaging a notched tappet-bar 18 attached to the signal lever. When an " authorizing" current is sent through from the end B of the section, the indicator represented by the line 21 closes a switch 23. Current from a battery 39 thereupon passes through a wire 38, switch 37 operated by signal lever, contacts 36, wire 35, switch 29, contact 30, wire 31, switch 23, electro-magnet 24, wire 34, and a low-resistance winding 20<a> of a lock electro-magnet 20. The magnet 24 holds its armature 25, and the switch 23 until the circuit is broken as hereinafter described. The excitation of the winding 20<a> causes the bolt 19 to be withdrawn, thereby unlocking the lever. As the bolt rises, it causes the switch 29 to move from the contact 30 to a contact 32. This breaks the circuit previously described, whereupon the switch 23 drops but simultaneously closes a second circuit, whereby current passes from battery 39 as before to switch 29 and thence by way of contact 32 and wire 33 to a high resistance winding 20<b> of the lock electro-magnet 20, so that the bolt 19 is retained in the unlocking position. The signalman is now at liberty to set the signal to " line clear." The movement of lever 14 transfers the switch 37 from the contacts 36 to contacts 40, whereby the second circuit is broken, with the result that the bolt 19 falls and back-locks the lever. At the same time the movement of the lever 14 couples by a switch 46 a pair of contacts 47 situated in a circuit subsequently closed in the manner hereinafter described. On the train entering the section it operates a switch 43 whereupon current passes from a battery 44 through a wire 42, contacts 40, switch 37, wires 41, 34 to the winding 20<a>. The bolt is thereupon raised, and with it the switch 29. This completes a circuit wherein current passes from the battery 39 through a wire 48, contacts 47, switch 46, wires 49, 35, switch 29, contact 32, wire 33, and winding 20<b>. The bolt 19 ia accordingly held up even after the circuit from the treadle 43 is broken after the passage of the train. The signals 12, 13, may be provided with electromagnetic reverses 45, 77 of any suitable type. When the signalman returns his lever to the "danger" position, the circuit of the magnet 20 is broken by the movement of the switch 46 and the bolt 19 again drops, so as to lock the lever in its original position. The " avthorizing " current for operating the indicator 21 is sent by the operation of a suitable manually operable member situated at the exit end of the section. In the example shown, this member consists of a plunger 57. On moving the plunger to accept a train, a detent 63 is moved to the left, whereupon a bolt 59, controlled by a magnet 60, drops and prevents a repetition of the "authorising" signal until the train has passed out of the section. The signal lever 49, which is not locked in the "danger" position, is now pulled over. At the same time, a switch 71 is raised to bridge a pair of contacts 72, and a bolt 54 of a lock electro-magnet 55 drops into a notch in a tappet-bar 53, thereby locking the lever 49. On the train leaving the section, it closes a switch 75, whereupon current passes from a battery 76 through a wire 74, contacts 72, switch 71, and wire 73 to the lock-magnet 55. This raises the bolt 54 and unlocks the lever. The signalman now resets his lever and opens the switch 72 and at the same time momentarily raises a switch 66 by means of slip mechanism 68, 69, whereupon current passes from a battery 65 through a wire 64, contacts 62, switch 66, and wire 61 to the magnet 60. The excitation of the electro-magnet 60 raises the bolt 59, which is retained in the raised position by the detent 63. This may be controlled by a magnet of which the circuit is governed from some extraneous source of control, for example the lever for the operating sidings points, the arrangement being such (1) that actuation of the plunger 57 will be prevented when the siding points are fouling the main road, (2) that the sidings points cannot be shifted from normal position after an " authorising " current has been sent by depressing the plunger. In the example illustrated, the detent 63 forms one arm of a counterweighted lever pivoted at 78 and carrying the armature 79 of an electro-magnet 80. A sidings point lever 84 carries a tappet bar 90, and is locked in the normal position by a bolt 91 of a lock electro-magnet 92. Normally, the lever 84 can be shifted by closing a pedal-switch 93, whereupon current passes from a battery 89 through a wire 88, contacts 87, wire 86, and switch 93 to the lock magnet 92. The bolt 91 is thereupon raised and the lever 84 is unlocked. Should an " authorizing " current, however, have been sent by depressing the plunger 57, the dropping of the bolt 59 separates the contacts 87 and the lever 84 cannot be unlocked by closing the pedal-switch 93. On the other hand, an " authorizing " current cannot be sent when the lever 84 is shifted, because the bolt 59 is released by the movement of the detent 63 caused by the attraction of the armature 79 to the magnet 80 excited by current passing from battery 89, wire 88, contacts 87, wire 86, contacts 82, switch 83, and wire 81. The restoration of the lever 84 to its normal position momentarily raises a switch 94, whereupon current passes from battery 89 through a wire 96, contacts 95, switch 84, wires 97 and 61, to the magnet 60. This raises the bolt 59 so that a train can be accepted. In a modification, the lever 49 can be adapted to be locked in both positions. The lever locks may conveniently be of the kind described in Specification 1422/09 and 12,757/11.