Patent GB-190609786-A (GB)
Title: An Improved Method of Electrical Detection Between Railway or Tramway Signals, Points, Facing Point Locks or Fouling Bars.
Filed: 1906-04-26
Granted: 1907-03-28
Abstract: 9786. McKenzie & Holland, and Edmonds, C. H. W. April 26. Safety and locking bars; interlocking-apparatus; controlling and locking signals; indicators.-In a method of electromechanical detection between railway or tramway signals, points, facing-point locks, or fouling-bars, operated by electro - pneumatic or other power, the operating current may be taken from the control wire which carries current for operating the points, through contacts controlled by the switch tongues, to a wire leading to locking-apparatus and contacts on the signal lever, which are connected to means for operating the signal. An electro-magnetic lock controlling the signal lever must be energized before the signal lever can be pulled over, so that, if the points are disarranged and the contacts broken, the signal cannot be operated, and if the signal is 'off' it goes to 'danger.' Similarly the lever cannot be put back to its normal position with the points disarranged. In Fig. 1, is shown the main line A, branch line B, and the corresponding signals A<1>, B<1>. To pull off signal B', the road will have to be set to go from A to B. The point lever is pulled over to close the contact 6, operating the points plunger and locking-bar in the well-known way, opening the contacts 11, 13 and closing contacts 12, 14. The catch handle of the lever for operating the signal B<1> is then pressed closing the contact 1 and allowing current to flow from the battery Z along the wire 18, contact 6, wires 19, 20, contact 12, wire 21, contact 14, wires 22, 23, and 24, contact 1, indication magnet lock 2, wire 25, and the contact 16 on the signal post to the return wire. The magnet lock 2 is thereby energized, and allows the lever of signal B' to be pulled over, closing the contact 1<b> and allowing current to flow from the battery Z through contact 6, wire 19, contact 12, wire 21, con'act 14, wires 22, 23, and 26, contact 1<b>, and wire 27 to the signal motor 100<b>, thereby working the signal B<1>. Should any failure occur at the switches, the contact 12 is opened and the signal returns to danger,' the lock 2 rendering it impossible to return the signal lever to normal until all the points are put right. Signal A' may be pulled off in a similar manner when the switch points have been moved and bolted in the normal position, as shown in Fig. 1. In a modification, one signal has reference to more than one pair of points. Figs. 4 and 5 show a convenient form of switch-detector contact-box. The box 10 is attached to the stock rail by bolts passing through the off-set plate 10<a>. A contact-maker 49 is pivoted at 50 and carries an insulated contact-strip 51. A blade 53 having a pivoted crossbar connected at either end to the switch tongues by rods 62, 64, Fig. 3, is adapted to work in guideways 54 in the box, and a roller 55 mounted thereon engages a slot 56 on the contact-making arm. Insulated contacts 11, 12 are secured by bolts 58, 59, and as the switch points are moved, say from normal to reverse, the blade 53 is operated through the roller 55, and the contact-maker swings over to make contact at 12. The mechanical means for operating the points and electric contacts is diagrammatically shown in Fig. 3 ; it comprises the usual facing point lock bar 65, connected to the motor 70 and the point-locking and detecting blades 66, 15 being the known indication contact box. In a further modification, two roads cross one another, necessitating the use of a fouling-bar which operates contacts, only one pair of contacts being required for any number of signals referring to the fouling-point. Should these contacts be broken, the signal lever cannot be pulled if in the normal position, while if it is in the 'off' position the signal lever returns to 'danger.'