Patent GB-191308746-A (GB)
Title: Improvements in and relating to Electro-pneumatic Systems and Apparatus for Railway Signalling and for Operating Points.
Filed: 1913-04-14
Granted: 1914-02-05
Abstract: 8746. Irving, E. C., and British Pneumatic Railway Signal Co. April 14. Fluid-pressure operation; electric control.-In a combination of apparatus for actuating points, signals, &c. by pneumatic motors controlled by electromagnetically-operated valves, the circuits to which are controlled by a hand lever or slide, the movement of the said hand lever or slide is completed by a pneumatic cylinder controlled by an electro - magnetic valve, the circuit of which is carried through contacts at the distant apparatus operated, and through an indication contact on the hand lever or slide, the latter contact being made only at the intermediate position of the hand-lever, and not at the fullstroke positions. The fluid pressure is maintained on the operating-motors until the handlever is moved to control the reverse movement. An economy switch may be used to open the circuit of the valve-controlling magnets when the apparatus operated is home in its end positions, but to close the circuit on slight movement from these positions. A pair of selecting- relavs with armatures interlocked are included in the indication circuits. Means are provided to prevent interference by leakage currents on the various leads. Fig. 1 shows an arrangement of apparatus for operating the switch points of a cross-over road, the cylinders and controlling- valves being the same as those described in Specification 13,740/08. The hand-slide 1 is provided with indication cylinders 2, 3 as described in Specification 183/00 and preferably also with a centre locking-notch as described in Specification 9936/03. The points D, E and slide 1 are shown in position for a through road. To set the cross-over road, the slide 1 is pulled as far as the shoulder 5<a> permits, and current passes from the positive main P, through contacts 8<a> to the magnets 20, 20<a>, which control the valves of motors to reverse the points. These valves and the valves of the indication cylinders may be of the kind shown in Specification 6553/01. Current then passes through the detector contacts 23<a>, 23 to the indication relay magnet 50. The armatures of the magnets 50, 50<a> are preferably interlocked in the manner described in Specification 13,831/09, [Class 38(v), Electric switches &c.], so that the magnet 50<a> must have dropped its armature, as it should do when the points are first opened, before the armature 53 can be raised to close the circuit of the magnet 16 through the contacts 14 of the slide. These contacts are closed by a contact 13 nn a member actuated from the slide through a pin and slot which causes the contact 14 to be closed only when the slide is in an intermediate position. The piston of cylinder 3 then completes the stroke of the slide 1. The magnets 20, 20<a> are continually energized so as to keep the pressure in the points-operating cylinders until the slide 1 is set back. In the event of leakage current entering the leads, the polarized relay 87 is energized either at once or when the points are reversed according to which lead is faulty. The magnet 87 may either actuate an alarm or cut off the power supply, and so prevent further movement of the points or the hand-lever. In a modified arrangement, the indication relay circuits are energized from a separate source of energy, and the current for the indication-cylinder valve magnets passes through the main contacts of the hand slide.