Patent GB-190305050-A (GB)
Title: Means for Safely Controlling Tramway Traffic over Railway Level Crossings.
Inventor: SYKES WILLIAM ROBERT
Filed: 1903-03-04
Granted: 1904-03-04
Abstract: 5050. Sykes, W. R. March 4. Crossing-gate signals ; interlocking ; stopping engines and trains.-Relates to a method of safely controlling the traffic at level crossings where a line of railway is crossed by a tramway, particularly an electric tramway, and consists of a system of combined electrical and mechanical control for the crossing-gates and signals. Fig. 1 shows a diagrammatic sketch of the arrangement, in which R, T are the railway and tramway tracks respectively, X the combined signal cabin, the instruments and connections being shown in the righthand top corner, G the crossing-gates, and M the tramway feeder cable. Supposing it is desired to allow a train to pass, the signalman first closes the gates G against the tramway, as shown, by means of the usual gear, and then locks them in position. When the gates are thus looked in their correct position, the wires 10, 19 are automatically connected, thus completing the circuit through the detector GI and contact-springs 15, 18 on the railway down and up home signal levers. The signalman must then "accept " the train on his block instrument, and set the instrument to " Train entering section," as usual. This operation causes a mechanical lock to be taken out of the corresponding home signal lever, whereupon the signalman grasps the lever handle so as to withdraw the lever catch from its notch. The corresponding contact spring 15 or 18 is thus pressed against the opposite contact, diverting the current from the indicator to the electromagnet 23 or 22. The electromagnet then releases the corresponding signal SR' or SR<1>, so that it can be pulled to the " line-clear " position. In the conductors C<1>, C<2>, which carry the current for the tramcar motors, insulated sections C<3>, C<4> are provided, which extend a suitable distance on either side of the crossing. These insulated sections receive current from the feeder M through a switch B, which is connected to the gate-locking bolt lever in such a manner that it becomes closed only when the gates are locked in their correct position. The feeder M also passes to the two switches D<1>, D<2>, which are so connected to the up and down tramway signals ST<1>, ST<2> that the corresponding switch is only closed when one of the signals is set to indicate " Line-clear." The insulated sections C<3>, C<4> are thus always " dead " unless the crossing-gates and signals are set to allow a tramcar to pass. The operations necessary for setting the crossing-gates and signals to allow a tram to pass are similar to those described for the railway system. Assuming that the tramway signals are electrically operated, the pulling of the tramway up home signal lever closes the relay switch 55, 53, energizing electromagnets 56, 58 from the tramway feeder, and thus operating the up home signal. This circuit is completed through a breaking contact E' and the common return of the system ; a similar arrangement is used for signal ST<2>. The circuit-breaking devices E<1>, E<2> are placed the length of a tramcar beyond the signals, and are adapted to be automatically operated from a passing tramcar so as to block the line behind it. When the tramway signals are once set at the " line-clear" position, they become " back-locked " by any of the known devices, so that the gates and other arrangements cannot be reversed until the car has passed the crossing and closed the contacts F<1>, F<2>, which releases the " back-lock."