Patent GB-420193-A (GB)
Title: Improvements in or relating to arrangements for safeguarding crossings on railway lines
IPC: B61L29/28
Filed: 1933-09-30
Abstract: 420,193. Level - crossing signals. NAAMLOOZE VENNOOTSCHAP MACHI. NERIEEN-EN APPARATEN FABRIEKEN, 30, Croeselaan, Utrecht, Holland. Sept. 30, 1933, No. 26983. Convention date, Nov. 12, 1932. [Class 105] A level -crossing has sections formed by insulated rail lengths A, C at each side thereof and preferably an insulated rail B at the actual crossing and has two track relays GRI, GRII each having an auxiliary relay HRI, HRII whereby the rail length B at the crossing is linked with the section A or C entered first and the clear signal is restored as soon as the train has left the actual crossing ; the dropping of track relay GRI, if section A is entered first, picks the auxiliary relay HRI (electrically interlocked by being picked over a back contact of the other relay HRII) whereupon the other track relay GRII is shunted and, on dropping, closes a stick circuit for the picked-up relay HRI which thus continues energized and prevents the relay HRII being picked up when section A is vacated, and further, as soon as section A is vacated the clear signal is lit over front contacts of relays GRI and HRI and a back contact of relay GRII. A train entering section A de-energizes the track relay GRI a contact 1 of which extinguishes the white clear signal and lights the red danger signal while back contact 2 causes an auxiliary relay HRI to be energized from battery HB through the said relay HRI and over back contact 2 of an auxiliary relay HRII, (for the other direction of travel), back contact 2 of relay GRI, resistance HWI, insulated rail A and the train axles to the earthed rail D and so back to battery HB. Front contact 4 of relay HRI links the insulated rail B at the crossing with the section A rail. The track relay GRII for section C is now short-circuited by front contact 3 of relay HRI and back contact 3 of track relay GRI. When the train passes the crossing and enters section C the relay HRI continues to be energized over a stick circuit including its own front contact 2, back contact 2 of track relay GRII, resistance HWII, insulated rail of section C and the train axles to the earthed rail D and battery HB. When the last axle leaves the linked sections A, B the track relay GRI is again energized and the white clear signal is thus at this time lit over front contact 1 of relay GRI, back contact 1 of relay GRII and front contact 1 of relay HRI. It should be noted that the resistances HWI, HWII are necessary to allow the relay GRI to be energized since the non-earthed side of relay GRI is connected to earth over resistance HWI, back contact 2 of relay GRI (before it has lifted), back contact 2 of relay HRII, front contact 2 of relay HRI, back contact 2 of relay GRII, resistance HWII, rail C, train axles, and earthed rail D. When the train finally leaves the region the relay GRII is re-energized and the stick circuit of relay HRI is broken since section C is now free of axles. The clear white signal is now lit over front contacts 1 of the relays GRI, GRII. For the other direction of travel the operation is similar, but relay HRII is picked and stuck instead of relay HRI.