Patent GB-438038-A (GB)
Title: Improvements relating to token systems of traffic control for railways and the like
IPC: B61L23/24
Filed: 1934-05-09
Abstract: 438,038. Token apparatus for controlling railway traffic. ROBERTS, W. S., Newby, Ruff Lane, Ormskirk, Lancashire, BURTON, J. H., Pine House, Signal Works Road, Fazakerley, Liverpool, and RAILWAY SIGNAL CO., Ltd., 40, Broadway, Westminster. May 9, 1934, No. 14012. [Class 105] The instruments in a token system for controlling traffic on railways are alternately responsive to alternating currents of two different frequencies or to two different code currents. The invention is shown applied to the long section instruments of a system adapted for long and short section working and is also applicable to a system adapted for ganger occupation. As shown, the short section instruments 13 are operated by normal and reverse direct currents over their line wires 10, 11, 12, while the long section instruments are operated by alternating currents of two different frequencies over these line wires which are in effective series for such alternating currents by reason of transformer or condenser couplings. The apparatus shown in the Figure is in the condition for short-section working, a long-section token having been obtained to put the long-section instruments out of phase and this token having been inserted and locked in a slide 45 at the station Z. The short-section working is effected by the usual normal or reverse current over the line wires 10, 11, 12 for the different sections. To change to long-section working the operators at X, Y, Z respectively obtain a shortsection token (for the sections WX, XY, YZ) and insert them in slides 23 at X and Y and in a slide 38 at Z, these slides then being pushed in to close contacts 17, 22 and 39, the slides 23 then being locked in such position. The slide 38 releases a mechanical lock on the slide 45 and an electrical lock is released when the operator at W transmits an alternating current to energize a transformer 41 and magnet 44 over contacts 40 of the slide 45 and contacts 39 of the slide 38, the line wires 10, 11, 12 being now coupled up at X and Y by transformers 18 /19 which are inserted over the contacts 17, 22 of the slides 23. The slide 45 can now be pushed in and the locked-in long-section token is extracted thereby locking the slide 38 and short-section token. The long-section token is now inserted in its instrument so that the two long-section instruments are brought into phase ; the longsection instrument at Z is now connected to the line wire 12 by the contact 46 of the pushed-in slide 45. To obtain a long-section token at Z the operator at W transmits a current of frequency f<1> which operates a relay 28 responding only to such frequency whereby a lock is released to allow withdrawal of a token. The withdrawal of the token changes over a commutator 31, 32 so that the instrument at Z can now only respond to or transmit a current of different frequency f<2> and thus no further token can be obtained until the token has been inserted in one or other long-section instrument either to restore the first instrument to transmit and respond to the frequency f<1> or to change the other instrument to transmit and respond to the frequency f To return to short-section working, a long-section token is obtained and inserted in the slide 45 which is then pulled out ; this action frees the slide 38 which is then pulled out and the short-section token therein is returned to the instrument at Z, thus permitting a short-section token (for section YZ) to be obtained at Y and inserted in a slide 36 at Y thereby to free the slide 23 and the locked-in short-section token (for section XY) which is then inserted in the instrument at Y. Similar action frees the slide 23 and the locked in short-section token at X. Code-selected relays may be used in place of the frequency-selected relays 28, 29. The slides 23 may be interlocked with an additional slide to effect the backlocking of the points and signals for longsection working over intermediate passing loops, but to permit operation of the points, as for detaching vehicles, the long-section token can be inserted in a further slide which releases the additional slide and so frees the points. A ganger's occupation token can be freed from a portable instrument hooked on to the line wire, the ganger tokens for the different sections being released by currents of frequencies different from those used for the through traffic tokens. Such release can only be effected after a through traffic token has been obtained and then inserted in an auxiliary device at the signal cabin.