Patent GB-190613711-A (GB)
Title: Improvements in Apparatus for Operating Railway Switch Points and Signals.
Inventor: JOHNSON ARTHUR HENRY
Filed: 1906-06-15
Granted: 1907-06-06
Abstract: 13,711. Johnson, A. H. June 15. Points and switches.-Relates to the operation of railway points and signals by electric power. In the arrangement shown in Fig. 1, for operating points, a continuous-current points motor m is employed, and, when the movement of the points is completed, a by-pass valve held closed by the electro-magnet v is opened to render further rotation of the motor ineffective in the manner described in Specification No. 11,005, A.D. 1905, this opening of the valve serving to break the circuit of the electro-magnet k of a gravity-controlled lock on the points and at the same time closing the contacts v<11> of an indication circuit as described below. The hand slide l for controlling the points is fitted with the usual tappet l<1> of the interlocking-frame, and with a slot i<11> of known form for preventing the completion of the movement of the slide until the indication impulse is received from the points. The slot i<11> co-operates with a pin i<1> on a rod operated by a small quarterturn alternating-current motor i. When it is desired to reverse the points, the slide l is drawn forwards until it is stopped by the pin i<1> at the shoulder adjacent to the rear inclined portion of the slot ill. The battery b then supplies current to the motor armature m through the contact spring h<11>, wire o', relay coil y, choking-coil n<1>, and motor field coil m<1>, returning by the wire k<1> and safety switch q<1>. A parallel circuit, closed simultaneously, includes the contact-spring h<11>, wire v<1>, by-pass valve coil v, and the electro-magnet k of the points lock. At the same time the battery b supplies current to a continuous-current motor d driving a small alternating-current generator a. When the points are completely reversed, the switch p<1>, p<11> connected with the points establishes contact at 3, 5 and 7, 9, and at the same time the by-pass valve is opened and contact made at v<11>. Alternating current then flows through a circuit comprising the wire a', relay tongue y', contacts 7, 9, v<11>, wire v<1>, condenser c, and alternating- current relay r. The resulting contact at r', r<11> closes the secondary circuit of the transformer t, t<1> through the motor i, and, as the primary circuit is established through the contacts 5, 3 and e', j, e, the motor i makes a quarter-turn and completes the movement of the slide l. The contact-springs j, h<1>, h<11> are thereby moved out of contact with the parts e', o, b<11>, and the operating and indicating circuits are opened. The motor then stops, and the by-pass valve closes. by gravity, re-establishing contact at z, z<1>. To return the points to the normal position, the slide l is pushed back, the operation being the same as before but in a reverse direction. Although the points motor may be set in motion by an accidental cross between one of the wires h', o' and a live battery wire, the points cannot be operated, for the by-pass valve would remain open, and the points lock would remain on. If an accidental cross occurs between the valve wire v<1> and a live battery wire, the lowresistance coil q of the safety switch shunts the valve magnet v and points-lock magnet k and opens the battery circuit at q<1>. Owing to the use of the alternating-current relay r, an accidental cross between the alternating-current main a' and either of the wires o<1>, h<1> does not cause the'operation of the motor i unless the indication of the due closing of the points is received through the entirely independent indication wire v<1>. In a modified system, the relay r is dispensed with, and a motor i is employed having two windings both of which must receive current in order that the motor may operate. The points-indicating switch p is in this case so arranged that the circuit of the alternator through one winding is completed through the wires h<1>, k<1>, and the circuit through the other winding is completed through the wires h<1>, v<1>. In a further modification, the alternator instead of being placed in the signal box is placed at the points, permanent field magnets being employed. The alternator is driven by a turbine arranged in the by-pass of the hydraulic device described in the Specification referred to above, so that, when the movement of the points is complete and the by-pass valve opens, the alternator sends the indication current to the signal box to complete the movement of the slide which controls the points. Fig. 5 shows a device designed to prevent the momentary contacts at h and o, which would otherwise be made in moving the slide l shown in Fig. 1 into its forward and backward positions respectively. The connexion between the battery b and the part b<1>, instead of being of a permanent character, is made through a contact-arm 11 which is caused to move over the fixed contact-lug d<11> by means of lugs 10, 12 on the extension 13 of the slide l. These lugs are so spaced that contact at 11, d<11> is only made during the forward stroke of the slide while the contact-spring h<1> is on the contact o, whereas the contact between the same parts is only made during the backward stroke of the slide while the contact-spring h<1> is on the contact h. According to the Provisional Specification, alternating currents may be used in the motoroperating circuits and continuous currents in the indication circuits, or the currents in both circuits may be of a similar character.