Patent GB-191106592-A (GB)
Title: Improvements in and in connection with Apparatus for Railway Signalling.
Inventor: FLETCHER GEORGE EDWIN
IPC: B61L23/16
Filed: 1911-03-16
Granted: 1912-03-18
Abstract: 6592. Fletcher, G. E. March 16. Combined electrical and mechanical systems. -In a non-automatic combined electrical and mechanical system, relays across the track rails are only energized as a train is about to enter a section by means of a second relay in a mannally-closed circuit, the armature of which lifts that of the track relay which controls the circuit of an electromagnetic signal-release device. The track relays are designed to hold but not to attract their armatures, thus giving more sensitive action. The closing relay circuit may be made dependent upon the advance cabin and upon track relays of the advance section. Arrangements are made for cutting out signal cabins. The whole or part only of the track may be track circuited and in some cases the track relay of one section may control the track circuit of the next section. Fig. 8 shows the arrangement of circuits for protecting a section 3 with a crossing 3<c>. A source of electric energy (either an alternator 7<b> or a battery 7<c>) is connected to one end of an insulated section of rails and the circuit of a relay 17 is connected either through a transformer 7<a> or directly to the other end of the section, this relay circuit including contacts on the hand-lever 4, an indicator 15, and contacts closed by the armature of the relay. The relay is de-energized either when a train is on the rails 3 or when the points are open, and is closed by mechanical operation of the armature 18 by the armature 20<a> of the relay 20. The parts are shown in the normal position with the section clear and the block instrument 14 in " line closed " position. When a rear cabin offers a train, the operator presses the plunger 23, thereby closing a circuit from battery 19 through contacts 22<a>, 22, 21 and coil 20. The armature 18 of relay 17 is moved to close contacts 16, 25 thus completing the circuit from the track' circuit through the relay 17, contacts 16, and indicator 15, which indicates " line clear " if the section is unoccupied. When the plunger 23 is released, the relay 20 is de-energized, and a circuit is closed from battery 24 through the block instrument contacts 12, 13, contacts 25, 26, 26<a>, relay 28, indicator 30, and signal-release magnet 29. The armature of relav 28 closes a circuit from contacts 26 through contacts 27 in parallel to the plunger 23 so that further actuation of this plunger has no effect on the apparatus. The energization of release magnet 29 enables the operator to pull off the signal 1 for the train. When the train enters the section 3, the magnet 17 is de-energized and opens its circuit and deenergizes the magnet 29. This circuit can only be re-made after the train has passed beyond the section 3. If desired, the block instrument may be omited and the contacts 10, 11 connected. Several modifications of the system for particular purposes are described; part only of the track may be track-circuited ; a second train may be passed into a section before the first has cleared ; an intermediate cabin may be cut out to join two sections for working as one long section. Signalling-instruments; miniature signals.- Fig. 7 shows a plunger for operating the closing- relays and for use as a permission key. The contacts are closed by pushing in the knob 4<a> against the action of the spring 2, thereby rocking the contact-carrying shaft 9 and the bell-crank connected to the dash-pot plunger 18. The rod 4 is loose in the piston 5, which can, therefore, only be replaced after lapse of a certain time by the spring 2 under control of the dash-pot. An indicator is also described which consists of a pivoted arm carrying a flag which hides a fixed inscription on the usual block instrument when in position in front of an opening in the casing. Slots, reversers, and like apparatus.-Two forms of electro-magnetic and mechanical signalreleasing apparatus are shown in Figs. 1 and 3. In each case, an electro-magnet 12 straightens the members 8, 10 of a toggle joint so as to enable the signal to be set by moving the member 13. A mechanical stop 16 also keeps the toggle joint extended if required. In the form shown in Fig. 1, the bevel-wheel shaft 6 is held so that the motion of the wheel 3 is transmitted to the wheel 4 if the magnet 12 is energized, but if the shaft 6 is free to move, the signal wire cannot be pulled. In the form shown in Fig. 3, the guide 4 is held in position by the magnet to keep the roller 5 in contact with the projection 3<a> on the bar 13, so that the member 6<b> on the bar 13<a> is lifted and the signal drawn off.