Patent GB-190105669-A (GB)
Title: Improvements in and connected with Pneumatic Apparatus for Operating Railway Signals, Points and the like
Inventor: DODGSON FRANK LEMONT
Filed: 1901-03-18
Granted: 1902-03-13
Abstract: 5669. Dodgson, F. L. March 18. Signalling and communicating between trains ; semaphore &c. signals ; controlling and locking signals; indicators &c., point or switch and signal ; contacts, elect r i c .-Relates to pneumatic apparatus for operating railway signals, points, crossing - gates, &c., and to electrical apparatus in conjunction therewith for automatically putting the signal to danger,' or automatically operating the switch &c., when a train or car comes on a particular section of the track. The invention is illustrated as applied to the pneumatic apparatus described in Specification No. 183, A.D. 1900, for operating semaphores. The rails Z, Z' of the section are insulated from the adjacent rails, and form part of the local circuit w, w<1>, S<1>, S<2>, which, while the section is clear, keeps the electromagnet S energized and the second circuit t', t<2> broken at the armatures. The circuit t<1>, t<2> contains an electromagnet T, the armature t of which is adapted to operate the valve Q. This valve, as shown in Fig. 4, comprises two valves q<5>, which normally, under the action of the spring q<7> on the valve spindle q<4>, connect the pipe q to the exhaust port q<3>, and cut off communication between the pipes q, x<100>. The pipe q is connected to the cylinder M, the piston m‹ of which is engaged by the slot m, m<l> in the operating lever or bar L. The piston i<1> of the indication cylinder I<10> is engaged in the slot l, l<1> in the bar L, the horizontal portions l, m of the two slots normally holding the pistons stationary. When the bar L is pulled to the left to lower the signal, which operation is effected as described in the prior Specification above quoted, the piston m<0> is moved down in the inclined slot m<1>, and the piston i<1> is moved down the incline l<3> into the horizontal slot l<1>. When a train or car comes on the section, the battery W is short-circuited through the wheels U, the electromagnet S is de-energized, and the circuit t', t<2> is completed through the electromagnet T, which thereupon raises the valves q<5>, and so connects the pipes q, x<100>, while cutting off the pipe q from the exhaust port q<3>. Air then passes through the valve Q from the supply X<1> to the cylinder M, and raises the piston m<0>, which, acting on the inclined slot m<1>, automatically returns the bar L so as to put the signal to ' danger.' The return movement of the bar is stopped before completion by the shoulder l<2> of the slot l engaging the piston i<1>, the bar being released when the piston is raised by the return pressure from the signal on the latter reaching the 'danger' position. So long as the section is occupied, the pressure in the cylinders M, I<10> prevents the bar L from being moved again to lower the signal. When the section is cleared, the magnet S becomes energized, and the magnet T de-energized the valve Q being then actuated by the spring q<7> to connect the cylinder M to exhaust. The return movement of the bar L is completed by hand, to connect the pipes o, p to exhaust. In case of the failure of the electrical apparatus, the pneumatic apparatus can be operated by the signalman in the ordinary manner.