Patent GB-359558-A (GB)
Title: Improvements in or relating to train control systems
IPC: B61L3/12
Filed: 1930-07-25
Abstract: 359,558. Train control and cab signalling systems. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. July 25, 1930, No. 22473. Convention date, Sept. 25, 1929. [Class 105.] A train control and cab signalling system employing a train carried magnetic receiver relay comprises in each block section a plurality of trackway magnet assemblies which are located at different points along the block section and are controlled by a plurality of devices each controlled in accordance with the traffic conditions existing in a different advance section so that the train apparatus receives at each of the points in a particular section an indication of the traffic conditions in a plurality of advance sections existing at the time that it passes any one such point. A train-carried receiver relay as described in Specification 355,337 is shown in Fig. 1. The track system is shown in Figs. 2 and 2a, with one block section CD divided into three sub-sections and a section DE having two sub-sections ; each sub-section in block CD is provided with track permanent and electromagnets P<1>, E<1> .. with track relays T<1> .. and associated relays A<2> .. which are only fully energized to close the circuit to the corresponding electromagnets El .. when the associated track relay T<1> .. is shunted by the train. The track magnets of the other sections, such as DE, are not shown. The track electromagnets E<1> .. of block CD and a wayside lamp signal S<4> at the entrance to block DE are appropriately energized by a signal control relay C<4> which together with a line relay L<6> is energized from a battery LB<5> over contacts of track relay T<6> of the block in advance of block CD and track relay T<4> of block CD. The de-energization of any sub-section track relay such as T<3> maintains the rear subsection track relays T<2>, T<l> de-energized by dropping the armature contact from the batteries 4. The apparatus is shown in the normal condition. When a train enters block CD the dropping of the armature of track relay T<1> causes line relay L<4> to drop its armature to complete a circuit from battery LB<4> over front contact of armature 14 of track relay T<4> to the " clear " lamp G of signal S<4> and to a pole changing relay PC which applies normal voltage from a battery TC to the line 24 over the front contact of lowest armature of relay T<4>; also, the increased current in relay A<2>, due to the shunting of track relay T<1>, lifts its armature to energize the track electromagnet E<1>. Similar actions take place when the train is in the other subsections of block CD. When the train enters block DE the track relay T4 drops its armatures so that contact 13 is open and therefore line relay L<4> remains de-energized, back contact 14 makes a circuit to the " stop" lamp R of signal S<4>, contact 15 opens to de-energize signal control relay C<4> and line relay L<6>, and the lowest contact cuts off the voltage from line 24. When the train leaves block DE the armatures of track relay T4 pick up but the signal control relay C<4> remains de-energized since its circuit is open at the contact of track relay T<6>. The dropped armature of signal control relay C<4> prepares a circuit to " caution " lamp Y of the signal S<4>, which is now however open at the armature of line relay L<4>, and de-energizes pole-changing relay PC so that reverse voltage is applied to the line 24. The train-carried apparatus gives a clear signal, caution signal, or stop signal, according as the track electromagnets E<1> .. are normally energized, reversely energized, or de-energized. With a train in the block beyond DE, a following train would therefore receive three caution signals in the block CD and a stop signal in the block DE. The caution and stop cab signals are accompanied by a brake application which can be cancelled if the driver is alert.