Patent GB-727232-A (GB)
Title: Improvements in or relating to railway interlocking apparatus
IPC: B61L23/12
Filed: 1950-10-10
Abstract: 727,232. Railway signaling. SOC. TECHNIQUE POUR L'INDUSTRIE NOUVELLE SOC. ANON. STIN. Oct. 10, 1950 [Oct. 13, 1949], No. 24747/50. Class 105. Railway block signalling apparatus in which the clearance of a wayside signal at the entrance station cannot be effected until a loop circuit extending to the station at the other end of the section and connecting the block signalling apparatus of the two stations, has been tested, and wherein arrangements are provided for long-section working by at times cutting out one or more intermediate stations, is arranged so that the advance sections in long-section working must first give a signal denoting that their loop circuits and block signalling apparatuses are working correctly before the first-section loop receives the signal that its loop and block signalling apparatus are working correctly and only then does the wayside signal at the entrance station go to the clear aspect. The apparatus includes at each station, such as station 2, a mechanically interlocked relay pair A2, Aa2, and another mechanically interlocked relay pair E2, Ea2 by which the wayside signals are controlled. The Figure shows only those portions of the apparatus necessary for an understanding of the working when the intermediate station 2 is required to be cut out and through-running from station 1 to station 3 established. When the intermediate station 2 is to be cut out a change-over switch is operated to reverse the contacts BD1, BD2 from the positions shown. If now the signalman at station 1 operates the lever for the wayside signal at that station a lever content S1 is closed, whereby a circuit is closed from +ve through relay Aa1 and over loop line L1 to relay E2 at station 2; the circuit includes contact BD1 of the station 2 cut-out switch at reverse and a front contact h of the latched-up relay A2; there is a parallel branch over back contact f of relay E2 but this opens and is latched up. It will be seen that meantime relays Aal and E2 continue energized and it should be noted that the previously latched-up relay A1 is dropped. A front contact e of the relay E2 now applies current over reverse contact BD2 of the station 2 cut-out switch to relay Aa2 and over the loop line L3 to the relay E3 at the far station 3; this circuit includes a back contact k of the relay E3 so that current through the relays Aa2 and E3 at once ceases but the relay E3 remains up by the mechanical latch of associated relay Ea3. The brief lifting of relay Aa2 drops the latched-up relay A2 so that the contact h thereof opens, but meanwhile (while relay Aa2 is energized) the relays Aa1 and E2 continue energized over a front contact g of the relay Aa2 until this relay Aa2 drops whereupon the current through relays Aa1 and E2 ceases (relay E2 remaining latched up). Both relays A1, Aa1 of the relay pair at station 1 now being dropped the clear aspect G of the wayside signal at station 1 is energized over signal lever contact S2 and back contacts c, d of the relays A1, Aa1. Specification 695,272 and Swiss Specification 269,022 are referred to.