Patent GB-189920510-A (GB)
Title: Improvements in or relating to Signalling Apparatus for Railways.
Inventor: DUNHAM CHARLES THOMAS
Filed: 1899-10-12
Granted: 1900-08-25
Abstract: 20,510. Dunham, C. T. Oct. 12. Fog and audible signals ; indicators and repeaters, signal; signalling to cabins; contacts, mechanical. - Detonators contained in the magazine A, mounted on the ordinary signal post &c., are fed singly through the chute C on to the rail B by means of the ejector D, which is operated, through the linkage E<7>, E<6>, E<5>, E<4>, E<3>, E<2>, from the balance lever E<1> and the signal connection E, when the ordinary signal is put to 'danger.' The ejector D is preferably provided with rollers D', which cause the detonator to travel faster than the ejector. The detonator F is provided with a tang F<1> and transverse projections F<2>, the projections being held between the abutment C<2> and the hooks C', to prevent displacement of the detonator from the rail. If the signal is put to `safety' before the train passes, the supporting-tongue C<3> is withdrawn, by the lever C' and link C<5>, from beneath the detonator, so that the latter falls from the rail. A pivoted cover C<6>, linked to the tongue C<3>, may be provided to protect the chute from dirt &c., and it may also be adapted to close the lower end of the chute when the detonator is in position on the rail, to prevent the gases resulting from the explosion of the detonator from passing up the chute. The tang F<1> of the detonator may close an electric circuit with the contact c', to indicate to the signalman that the detonator is on the rail. The explosion of the detonator may also act, through a vane N and link N<2>, to close a similar indicating-circuit between the weighted contact lever N' and the contact N<5>. A projection N<8> on a slide connected to the signal-operating mechanism engages the lever N', to re-set the contact-apparatus when the signal is put to 'safety,' the lever N<7> working between the stops N<6> on the link N<2>. The movement of the signal to 'safety' may be indicated at the semaphore by the extension D<2> of the carrier D striking the bell D<3>, or by a pneumatically or hydraulically operated whistle &c., or an electric bell, actuated by the movement of the signal lever. When a signal is at 'safety,' this is indicated to the driver of an approaching train, by a bell, hooter, or other audible signal, which is actuated by a train-operated treadle. This operating-mechanism is disengaged by a connection with the signal lever, when the signal is put to 'danger,' the detonator mechanism then serving to indicate the position of the signal. Both positions of distant signals may be indicated by two train-operated audible signals, one of which is always operative, while the other is controlled by a connection with the signal, so that it is only operative in one position of the latter. If a train is waiting at a signal, this is shown in the signal cabin by the indicator M, Fig. 7, which is operated hydraulically, pneumatically, or otherwise from a train-actuated treadle. The indicating-tablet is carried by a plunger M<2> mounted in the cylinder M<1>. If the signal is at ' danger,' the tablet, when raised into view by the first operation of the treadle, is locked in the raised position by the detent M<3> engaging the hook M'. If the signal is at safety,' the detent is disengaged, through the connection M<5> with the signal lever, so that the indicator rises and falls as each pair of wheels passes the treadle. An audible signal may be employed in addition to, or instead of, the indicator M. At junctions, the leads of all the junction semaphores may be arranged to operate the same detonator mechanism. In this case, the detonator is placed on the line by counterweight when all the signals are at 'danger,' and is withdrawn when any one of the signals is put to 'safety.' The detonator mechanism may also be arranged to give signals by varying numbers of detonators, under the control of one or more semaphore levers, as required.