Patent GB-440048-A (GB)
Title: Improvements relating to the remote control of railway track switches and signals
IPC: A23F5/44
Filed: 1934-08-17
Abstract: 440,048. Electric interlocking systems for railways. GENERAL RAILWAY SIGNAL CO., Rochester, New York, U.S.A. Aug. 17, 1934, No. 23780. Convention date, Sept. 12, 1933. [Class 105] Points and associated signals are electrically interlocked by an interlocking relay which must be in the energized condition to permit the operation of the points in response to a control applied from the cabin to a points control relay and which interlocking relay must be in the de-energized condition to permit the clearance of a signal in response to a signal control applied from the cabin. Approach locking may be included in the control of the interlocking relay. The invention is applicable to direct wire and selector systems for remote operation of points and signals. The points control is such that the points are automatically restored should they be displaced from any cause and further if the polarized points control relay should fail to respond the operation of the cabin signal lever is ineffective to clear a signal. The Figure shows the apparatus in the state with the points at normal and the signals at danger. The points machine SM is controlled by the polarized relay WZ and a stick relay LS. A polarized points-position relay WP is energized when the points have been moved over and locked. A relay NW or RW is energized when the relays WZ, WP are in correspondence denoting the completion of the points operation. The cabin apparatus is shown at the left and includes a points repeater relay WPP and a lock repeating relay LP. The relay LP has two coils differentially wound so that reversal of the current by the lever SML does not drop the relay. To set the points to the reverse position the points lever SML is operated and snaps over so that the relay LP has not time to drop its contact 8 and so continues to be energized through its lower winding from the negative side of battery 48, the current flowing over contact 8, contact 9 of relay WPP still at normal, to the relay WZ. Relay WZ sets its contacts to reverse so that the relay NW is de-energized as the settings of the contacts 20, 23 of relays WZ and WP do not now correspond. The relay LS is now energized over the back contacts 16, 17 of the relays NW, RW and so the points machine SM is supplied over the contacts 25, 26 of the relay LS and the contacts 27, 28 of the relay WZ at reverse. When the points have been moved over and locked, the points-position relay WP is energized reversely and the contact settings of the relays WP, WZ now being in correspondence and at reverse the relay RW is energized. This breaks the circuit to the relay LS. The cabin points repeater relay WPP moves contact 9 to the reverse position so that the current no longer passes over the contact 8. The points are returned to normal in a similar manner on moving the cabin lever SML to normal. To clear an East-bound signal the cabin lever SGL is moved to the right (closing the left contact) so that current flows from the positive side of battery 48 to the polarized signal control relay GZ which opens its contact 39 to de-energize relay L. The points being assumed at normal then a signal relay IG for clearing a signal 1 is energized over back contacts 29, 30 of the relays LS, L, front and normal contacts 31, 32 of relay GZ, and front contact 33 of relay NW. If the points are at reverse then the current flows over contact 34 of relay RW (instead of contact 33 of relay NW) to a relay IAG so clearing a signal IA. To clear a West-bound signal the lever SGL is moved to the left and in a similar manner clears a signal 2 or 2A according to the setting of the points. When the signal lever SGL has been set to clear a signal the relay L is de-energized and thus drops its contact 10 so that the points control relay WZ is energized by its stick circuit and cannot therefore be affected by any operation of the points lever SML. Moreover after any such movement of the points lever it must be returned to the position corresponding with the points setting since the contact 8 of the cabin relay LP dropped when the contact 10 of relay L dropped; thus, the signal lever SGL having been returned to neutral, the points lever SML must be set to correspond with the contact 9 of the points repeater relay WPP to pick up the relay LP and close its contact 8. Only when contact 8 is closed can the opposite polarity current be applied to change over the points control relay WZ. The relay LS by being stuck up ensures that the points movement is completed even if the signal lever is operated during such movement since the opening of the contact 18 of relay L does not de-energize the relay LS. With a train on the detector section, so dropping the relay T, the points may be moved by hand operation. The relays NW, RW are thereupon dropped since the relays WP, WZ go out of correspondence, but as the contact 15 of relay T is open the relay LS is not energized and so the points machine is not supplied with power. When the section is vacated the relay LS is energized and power is supplied to the points machine to restore the setting to agree with the points control relay WZ. A similar automatic return of the points is effected if they are displaced from any cause. If the points control relay WZ should fail to move its contacts when a changed polarity is applied and it is then attempted to clear a signal no signal will be cleared since the current flow arising in the stick circuit for the relay WZ when the relay L is dropped to open its contact 10 is opposite to the current applied from the line 46 and therefore the relay WZ drops its neutral contacts 11, 21 when the decaying original flux approaches zero. Thus the relays NW, RW are both dead so that contacts 33 .. 36 thereof are open and prevent a signal being cleared. Specifications 169,795 and 338,826, [both in Class 105], are referred to.