Patent GB-115035-A (GB)
Title: Improvements in and relating to Railway Traffic Controlling Apparatus.
IPC: B61L3/22
Filed: 1918-04-15
Abstract: 115,035. McKenzie, Holland, & Westinghouse Power Signal Co., (Assignees of Lewis, L. V.). April 16, 1917, [Convention date]. Fluid-pressure.-Alternating current supplied to the track rails and controlled automatically, is transmitted inductively to apparatus on the train to effect a reduction in the speed of the train after a predetermined distance is traversed. Fig. 2 shows the apparatus on the train, which comprises a venting valve actuated by a speed-controlled governor against the action of springs put in action by electromagnetically-controlled pneumatic cylinders. It also includes a slow-acting contact-breaker which is actuated pneumatically to open the circuit when the train has travelled a predetermined distance after de-energization of the magnet Q. The track is divided into insulated sections and each section has connected to the rails at one end one coil of a two-coil relay. Current of one or two frequencies is supplied to the other end of each section by a transformer, the primary of which is connected to one or two sources of supply according to the condition of the section ahead. The rails of the section in rear of a train are supplied with current of one frequency, say 60, and the rails of the sections further in rear with current of another frequency, say 90. The track relays also close the circuit from one source of energy to auxiliary rails at predetermined points along the track. The train carries coils 32, 32<a> in inductive relation to the track rails and connected through a tuned circuit to a vacuum amplifying-device G by means of which the relay D is energized when current of 90 cycles is applied to the track rails. A coil 32<b>, in inductive relation to the auxiliary conductors K, controls the relay D<1> when certain rails are passed while energized. The relay D controls the magnets H, M, Q. The magnets H, M control valves by means of which, when the magnets are erergized, pressure fluid is supplied to the cylinders 22, 25. The pistons of these cylinders form abutments for springs 20, 27 which act upon the valve-spindle 17, the parts being proportioned so that, when neither magnet is energized, as shown, only slight force is exerted by the spring 20. When magnet H is energized, this spring is compressed by the piston 21 and acts with great force on the valve spindle 17. When magnet M is energized, the piston 24 exerts an intermediate pressure owing to the shorter length of the cylinder 25. The valve is moved against the action of the springs by a collar 15 of a centrifugal governor mechanism driven from a train axle and is thus opened at a low speed if neither magnet is energized, and at a high speed if magnet H is energized. So long as current from source 90 is supplied to the track rails A-B, a train running thereon will have the magnets D and H energized and high speed is possible. On passing into section B-C, immediately in rear of an occupied section, the magnet D drops its contacts and magnet H is de-energized and magnets M, Q are energized. Magnet M being energized permits the train to proceed at intermediate speed. Magnet Q puts in operation the slow-acting device J which causes the circuit to the magnet M to be broken at contacts 41 after a given distance has been traversed by the train. When energized, the magnet Q causes the valve 51 to pass fluid from pressure pipe 72 to the cylinder 48, and a spring moves the piston 47 to the right, and sets the valve 46 so that the reservoir N is charged from the pipe 71 and the piston 42 closes contacts 41. When magnet Q is de-energized, the valve 46 is reset to the position shown and fluid escapes from the reservoir N through the rotary valve 49 which is driven from a train axle and permits small quantities of fluid to escape at each revolution, thus gradually reducing the pres. sure in reservoir N. When the pressure is sufficiently reduced, the spring 44 opens the contacts 41 and de-energizes the magnet M so that the valve 18 will be opened if the speed exceeds the predetermined minimum value. The magnet D, when energized as each energized rail is passed, serves to energize the magnet Q for the purpose of resetting the slow acting device; by placing the rails at suitable positions, the length of track over which the train may pass at medium speed may be varied as required.