Patent GB-190508523-A (GB)
Title: Improvements in or relating to Railway Signalling Systems.
Inventor: SCHOLZ KARL
Filed: 1905-04-20
Granted: 1906-04-19
Abstract: 8523. Scholz, K. April 20. Spark-gap apparatus ; wireless signalling ; switches.-In an automatic railway signalling-system, use is made of the reduction of resistance of an electric spark-gap when ultra-voilet light rays fall upon it. A sender comprising an electric arc lamp with a special reflector and a receiver comprising the spark-gap of an induction coil are carried on the engine and on the last carriage of each train, and alarms on the engine are sounded and the air brakes automatically applied when two trains approach too closely. Contact-rails and stationary senders are provided at sharp curves and at the other places for actuation in conjunction with contactbrushes on the trains. Under special conditions at sharp curves, the use of the ultra-violet rays is dispensed with, the system acting as an automatic electric system. The electric arc lamp, Fig. 6, constituting the sender is of a well-known type capable of withstanding vibration, in which the carbon-holders 7, 8 are carried by pistons 5, 6 in two cylinders 1, 2 with a connecting-passage 4, the spaces below the pistons being filled with a heavy liquid such as oil or glycerine. A piston slides in a cylinder 11 perpendicularly to the passage 4, and is provided with a hole connecting the ports 12, 13 in one position of the piston. Another port permanently connects the cylinders 1, 11, and the piston for the cylinder 11 is attached to a pivoted arm 16 actuated by the armiture of an electromagnet 22 against a coiled spring 18. The piston 6 is primarily in its upper position and the piston 5 in its lower position, and the coiled spring 18 moves its attached piston, so connecting the ports 12, 13, when the weight of the holder 8 causes its descent so that the carbons touch and a current flows through an electro-magnet 22. The piston of the cylinder 11 is thus actuated to cut off the connexion between the ports 12, 13, so striking an arc by the descent of the lower carbon, a small quantity of the liquid passing out of the cylinder 1 into the cylinder 11. When the arc lengthens and reduces the current through the electro-magnet 22, the spring 18 again actuates the piston of the cylinder 11 and places the cylinders 1, 2 in communication, when feed of the carbons is obtained by the greater weight of the holder 8, a small quantity of liquid simultaneously passing from the cylinder 2 to the cylinder 1. A reflector 27 of any known construction surrounds the arc and is mounted to turn around the axis of the carbons in a bearing 26. A cylindrical cover 28 is provided on the reflector, and a rectangular slit 29 is formed therein through which a slightly diverging horizontal beam of light is sent through a biconvex lens of rock-crystal which permits the passage of ultra-violet rays. A forked metal piece 32 attached to the bearing 25 is placed in front of the slit, and interrupts the beam on a very sharp curve when the reflector is excessively turned from its normal position. When the train passes round curves, the beam of light is arranged to cut the arc of track at a predetermined distance, say 300 metres, this being obtained by turning the reflector automatically by means of an attached arm 34 and a connecting-rod 38, Fig. 7, which is attached to the arm 34 and to a pivoted balance beam 43 by pin joints allowing movement in two perpendicular planes at its ends. The balance beam 43 is attached through links 50 and rods 49 to the pistons or floats of two vertical cylinders 45, which are connected by tubes 47, 48 and contain a liquid like petroleum. Since the rails are fixed at different heights at curves, the difference in height increasing with the curvature, the locomotive is correspondingly tilted and the balance beam 43 is actuated by the floats so that the reflector is turned from its normal position. The receiver, Fig. 6, is fixed to the sender casing 33 and comprises a spark-gap between platinum foil coated electrodes 55, 56 contained in rarefied air or gas. A quartz window 54 and a biconvex rock-crystal lens 52 are provided. Fig. 10 shows the circuits emplcyed in the system, the left-hand portion showing the circuits and apparatus employed on a locomotive and the right-hand portion that employed on a last carriage. Both on the locomotive and on the last carriage a dynamo 59 driven when the train is in motion and a secondary battery 60 provide the sources of current, the latter being employed when the train is at rest and being provided with any automatic switching-off device for actuation when the battery is fully charged. The sender arc lamps are directly connected to the dynamos and secondary batteries, which are also shunted through the primaries of induction coils I, which include the receiver spark-gaps 51 and relay solenoids 65 in their secondary circuits. These relays 65 through armature contacts 68 control shunted circuits from the dynamos and secondary batteries through alarms K, L on the engine and through air-brakeoperating solenoids 75, although the last carriage circuit includes only the alarm K. Thus the ultraviolet beam falling upon either receiver spark-gap 51 lowers its resistance and allows sparks to pass, so energizing the relays 65 and closing the alarm circuits, and, if the engine receiver is actuated, also actuating the air brakes but if the last carriage receiver only is actuated merely sounding the alarm K. Tne driver is thus warned to leave the following train. At extremely sharp curves, contact-rails 95, 96 are provided for brushes 94 on the engine and last carriage with other brushes 112 connected through resistances 113, and relatively disposed as shown in Fig. 10. The brushes 94 are connected through reversible switches 83-to be reversed when the train travels in the opposite direction-which are provided with pivoted arms 82, 84 and a connecting-link 83, to solenoids 78, the plungers 79 of which are carried by a balance beam 77. This beam, shown diagrammatically in Fig. 10, is really mounted on the pin of the armature 66 of the relay 65, and carries an arm 87 which mechanically throws over the armature 66 to close the contact 68 under the special conditions when two trains enter upon a curve from opposite directions. A circuit is then completed through the solenoids 78 and the dynamos 59 of both trains in series, and the double electrical pressure thereby produced actuates the solenoids 78 and causes the arm 87 to throw over the relay armature 66 and close the contacts 68 in both trains, thereby applying both brakes. Normally, a train entering upon a curve lights up stationary sender arc lamps O, P at the ends of the curve, current for this purpose passing from the engine dynamo through the brushes 94. When an engine travelling from left to right, say, in Fig. 10, has passed the sender O, the brushes 112 shortcircuit the sender O and also prevent current from passing to the apparatus on the last carriage from the locomotive. The brushes 94 on the last carriage will again light up the sender O on passing it. Contact-rails and stationary senders are similarly mounted at each block signal and at stations, and a screen on a pivoted lever actuated in conjunction with the semaphore arm covers the slit of the sender apparatus when the signal is at 'safety' and removes it at 'danger.' The contact-rails and brushes may be replaced by overhead conductors and trollys carried on trolly poles on the train.