479,206. Railway signalling. GLENN, S. L., WOODHOUSE, J., and GENERAL RAILWAY SIGNAL CO., Ltd. Aug. 15, 1936, No. 22534. [Class 105] Railway signalling-apparatus in which points are set and a signal cleared by operating on a control panel the two manual devices corresponding to the entrance and exit ends of a route is provided with outer and inner signals for the points, but the outer signal does not clear unless an" overlap " beyond the inner signal and in the route established by the points is free. Fig. 1 shows a track lay-out and Fig. 2 the control arrangements therefor with control buttons provided on a miniature diagram. In order to set up a route over the points 5TS at normal and to clear the outer signal 40, the operator sets the entrance button 40BT and briefly operates the exit button MBT in the " main " line on the diagram. A route relay 40MR is thus picked up over button' contacts 2, 3 and thereafter sticks over the entrance button contact 2 alone. A contact 5 of the route relay energizes a polar points-control relay 5WZZ normally, provided that a lock relay 5L is energized and closing its contact 6. The points are thus set normal by energization of the points motor 5SM over contacts 47, 48 of the lock relay 5L and relay 5WZZ. On completion of the points movement, there is energized a polar points-indication relay 5KR, of which contacts 9, 8 now energize a normal correspondence relay 5NWR. The lock relay 5L is now de-energized since its circuit at this time proceeds over a front contact 11 of the relay 5WZZ to an open contact 10 of the relay 5NWR. With the lock relay 5L de-onergized (so locking the points 5TS against operation), a circuit for the relay 40HR (by which the outer signal 40 is cleared) is closed over back contact 12 of the lock relay 5L, front contact 13 of the correspondence relay 5NWR, front contact 14 of the route relay 40MR, and front contacts 15, 16, 17 of the track relays 700TR, 900TR, 500TR. Thus it will be seen that for the outer signal 40 to clear it is necessary that the overlap section 700T beyond the inner signal 30A-B-C at the points 5TS be unoccupied. The signal does not of course clear if the approach section 900T or the points-fouling section 500T are occupied. To clear the main line inner signal 30A at the points, the operator moves the button 30BT clockwise and briefly operates the button M1BT. Route relay 30MR is thus picked up over contact 19, the circuit including the stick contact of the route relay 40MR (already picked up). A front contact 23 of the relay 30MR picks up a route relay 30MMR over contact 22 of exit button M1BT. With these conditions, the signal 30A is cleared by the relay 30AHR being energized over back contact 12 of the lock relay 5L, front contact 13 of correspondence relay 5NWR, front contacts 21, 24 of the route relays 30MR, 30MMR, front contacts 25, 26, 27, 28 of track relays 200TR, 500TR, 600TR, 700TR, contact 29 closed with button 30BT moved clockwise, back contact 30 of a lock relay 2.3L (deenergized as described below) and front contact 31 of a correspondence relay 2.3NWR. Thus the inner signal 30A only clears provided that an overlap section 200T beyond the next signal 20 is free. The intervening sections 500T, 700T, 600T must of course be free and a cross-over 2TS-3TS situated in the overlap section 200T must be at normal. It should be noted that a contact 32 of the route relay 30MMR energized a polar points-control relay 2.3WZZ to set the cross-over 2.3TS to normal with subsequent energization of the corre. spondence relay 2.3NWR and de-energization of the look relay 2.3L as required above for the signal 30A to clear. A change of the points is not possible if the section which would constitute the new overlap is occupied. For example, the points 5TS can be altered only if the lock relay 5L is energized. Assuming that the signals have been returned to danger by restoration of the panel buttons then a circuit for the relay 5L extends from -ve, through the relay 5L, over back contact 11 of the now de-energized relay 5WZZ, front contact 100 of the fouling section track relay 500TR, front contact 101 of ahead section track relay 700TR at present paralleled by normal contact 114 of the points repeater relay 5KR, front contact 102 of track relay 800TR for the section 800T which would form the new " overlap," and thence through contacts 103, 104-105, 106-8, of the signal relay 40HR, of a time-element approachlocking relay 30JS, and of signal relays 30AHR, 30BHR, 30CHR. It will thus be seen that if section 800T, which would be the new " overlap," is occupied then the points cannot be changed. The presence of a vehicle in the existing overlap section 700T does not prevent the energization of the lock relay 5L since the opening of the track relay contact 101 is ineffective by reason of a parallel closure by the normal contact 114 of the points indication relay 5HR. To set the points and clear the signals 40, 30B for the loop line, first the buttons 40BT and LBT are operated, thereby energizing a route relay 40LR which sets the points 5TS at reverse and clears the signal 40 in a manner similar to that already described, but the overlap is now provided by the section 800T since the circuit to the signal relay 40HR now includes contact 49 of the reverse correspondence relay 5RWR and front contact 51 of the track relay 800TR. If now the operator wishes to clear the signal 30B to allow movement on to the loop, he operates the button 30BT clockwise whereby a contact 53 is closed to pick up a route relay 30 LR by a circuit including the stick contact of the relay 40LR. Next he operates button MIBT (assuming he wishes to set the loop-line exit to the main line) whereby a route relay 30LMR is picked up over a contact 55 of the relay 30LR. This route relay 30LMR by its contact 59 energizes a relay 4WZZ whereby a de-rail 4TS is set so as to prevent any vehicle from a siding S reaching the loop line ; in addition a contact 57' of this relay 30LMR reversely energizes the relay 2.3 WZZ whereby the cross-over 2TS-3TS is put at reverse. The signal 30B is thus cleared by a circuit from + ve, over back contact 12 of lock relay 5L, front contact 49 of reverse correspondence relay 5RWR, front contact 54 of route relay 30LR, front contact 56 of route relay 30LMR, front contact 66 of normal correspondence relay 4NWR for the de-rail 4TS, back contact 65 of look relay 4L, front contact 67 of the track relay 200TR, front contact 68 of the reverse correspondence relay 2.3RWR, contact 69, front contacts 70, 71, 72, 73 of the track relays 800TR, 500TR, 400TR, 300TR, back contact 74 of lock relay 2.3L, and winding of the signal relay 30BHR. Thus for the signal 30B to clear not only must the overlap section 200T be unoccupied but also the de-rail 4TS must be set so that no vehicle from the siding S can reach the loop line. If, however, the operator desires to set the loop-line exit to the siding, he operates a button SBT instead of the button MIBT. In this case a route relay 30SR is energized by a contact 79 of the relay 30LR. The route relay 30SR sets the cross-over at normal. The button SBT also closes a contact 85 whereby a circuit is completed from +ve, over a back contact 84 (controlled by a button 50BT which has not yet been operated), the contact 85 of the siding button SBT to the normal winding of the relay 4WZZ. Thus, the de-rail is set and on the lock relay 4L becoming de-energized, the signal relay 30BHR is energized by a circuit from +ve over back contact 12, front contacts 49, 54, 82, 86, back contact 87, front contact 88 of normal correspondence relay 2.3NWR, front contacts 69, 70, 71, 72, 73, back contact 74, and winding of signal relay 30BHR. It will be seen that in this case the clearing of the signal requires the overlap section 300T to be free and with the de-rail set to divert any vehicle coming from the siding. To clear the signal 50B to allow the train to enter the siding the operator now operates button 50BT counterclockwise to energize a relay 50BR, of which front contact 84 picks up a route relay 50 SR. A contact 90 of the relay 50SR reversely energizes the relay 4WZZ whereby the de-rail is put at reverse to establish rail continuity. The signal 50B is then cleared by a circuit (not shown) controlled by the route relay 50SR and by other control conditions. It should be noted that the circuit for signal relay 30BHR now includes contacts 92, 93 of the route relay 50SR and reverse correspondence relay 4RWR instead of contact 86 of the normal correspondence relay 4NWR. The panel has miniature points such as 5ts controlled by the correspondence relays 5NWR, 5RWR and lock lights such as LL controlled by the lock relay 5L. The operating buttons may be situated on a control board separate from the miniature diagram. Specification 440,765 is referred to.