Patent GB-477847-A (GB)
Title: Improvements relating to apparatus for controlling railway switches and the like
IPC: B61L21/06
Filed: 1936-07-06
Abstract: 477,847. Operating railway switches. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 6, 1936, No. 18716. Convention date, Dec. 10, 1935. [Classes 104 (i) and 105] Apparatus for controlling railway switches, &c. comprises electrically controlled mechanism, e.g. an electropneumatic machine M, for operating the switch in accordance with the setting of a control lever L, and means, when the switch is displaced by being trailed through, to cause the mechanism to complete the displacement to the opposite position, the switch being automatically returned to its original position after the train has passed the switch. The machine M has normal and reverse magnets N, R, adapted to be alternately energized, and the switch E is operatively connected to a circuit controller G comprising three movable contacts 4, 5, 6, co-operating with fixed contacts 4a, 4b, 5a, 5b, 6a, 6b. Contact 4-4a is closed when E is at normal or at any position between normal and mid-position; contact 4-4b is closed when E is at reverse, or at any position between reverse and mid-position ; contact 5-5a is closed when E is at any position but full reverse ; contact 5-5b is closed only when E is at full reverse ; contact 6-6a is closed only when E is at full normal ; and 6-6b is closed when E is at any position but normal. The magnets N, R are controlled by the controller G, a track relay D, and a hand control lever L. The lever L has two positions n, r and is connected to a contact arm 7 which co-operates with two fixed contacts 7n, 7r. If L is at n and the track section B-C is unoccupied, magnets N, R and lamp H<2> are dead, but lamp H<1> is lighted over a normal indication circuit from battery K through 9, 7-7n, H<1>, front contact 10 of relay D, contact 6-6a, and wires 11, 12 to battery. If L is moved to reverse position, the lamp H<1> is extinguished, contacts 7-7r are closed, so that magnet R is energized through a circuit from battery K through 9, 7-7r, lamp H<2>, contact 13 of D, contact 5-5a, wire 14, magnet R, and wire 12 to K, and switch E is moved to reverse, opening contact 5-5a and closing 5-5b. This deenergizes R and M and completes a reverse indication circuit from battery K through 9, 7-7r, lamp H<2>, contacts 13, 5-5b, and wire 12 to battery. When a train enters the track section B-C, relay D is de-energized, opening contacts 10, 13 and closing contact 17. This interrupts the control circuits of magnets N, R, thus preventing operation of the switch by lever L and extinguishing lamp H<1>. If, with E in normal position, a train trails the switch, D is deenergized and will complete a circuit from K through resistor J<3>, contacts 17, 4-4a, wire 18, contact 6-6a, wires 11, 12 to K. When the switch is slightly displaced by the wheels, 6-6a will open and break this circuit, while 6-6b will close and complete an auxiliary control circuit for magnet N from K through 9, resistor J<3>, contacts 17, 4-4a, wire 18, contact 6-6b, magnet N and wire 12 to K. Magnet N will tend to return E to normal, but the counter force of the wheels will move the switch towards reverse, and as soon as it passes mid-position, the opening of 4-4a will de-energize N, and the closing of 4-4b will complete a circuit for magnet R including contacts 4-4b and 17, and R will complete the movement of E to reverse. Contact 5-5a then opens, de-energizing R, and contact 5-5b will close. When the train leaves section B-C, relay D will pick up and complete the normal circuit for N, which will then restore E to normal. The resultant closing of 6-6a will light the normal indication lamp H<1>. In another form the two lamps may be replaced by a single lamp connected in series with the control and indication circuits shown in Fig. 1. In another form, a relay is connected in series with the control and indication circuits and controls a contact in series with the single lamp mentioned above. In another form, two lamps are controlled jointly by the above relay and a second pair of contacts operated by the lever L. In another form, the number of line wires is decreased by replacing the three relay contacts 10, 13, 17 by a single two-way contact. In another form; the normal control circuits of the magnets includes a contact operated by a relay controlled by a lightsensitive device arranged across the switch, so that a passing train interrupts the beam and de-energizes the' relay until the train has passed the switch, which is arranged outside the section B-C. In another form, the normal magnet circuits are controlled by two relays under the control of two lightsensitive devices arranged across the track, so that when a train cuts the beam of the first one, a circuit is made which energizes the magnet N to hold the switch E at normal. When the train cuts the beam of the second device, its relay is de-energized and interrupts the pick-up circuit of the first relay until the train has completely passed. The second relay then picks up and completes the pick-up circuit of the first relay to de-energize the magnet. In another form, the layout of Fig. 1 is rearranged so that a single lamp is capable of giving three distinctive indications, and is not included in any of the control circuits. In a modification of Fig. 1 the control and indication circuits are separated, and two batteries and a number of rectifiers are provided to permit the use of a minimum number of wires between the lever L and the switch. In a modification of this form, the circuit controller G has two additional contacts to eliminate one rectifier from the previous arrangement. In another form, the switch mechanism is arranged so that if the switch is trailed, it will remain in its trailed position until the lever L is moved to a position corresponding to the new position, after which the switch may be restored to its original position by restoring L to its original position. In a modification of this form, the track relay D is controlled by a second relay, which is jointly controlled by lever L and the circuit controller G. In a further modification, the second relay above is made slow releasing, and is controlled by lever L, relay D and controller G in such a way that it will be energized when and only when the switch and lever occupy corresponding positions and relay D is de-energized.