Patent GB-190712485-A (GB)
Title: Improvements in Apparatus for Operating Railway Switch Points and Signals.
Inventor: JOHNSON ARTHUR HENRY
Filed: 1907-05-30
Granted: 1908-05-28
Abstract: 12,485. Johnson, A. H. May 30. Points and switches.-Modifications in the apparatus described in Specifications No. 11,005, A.D. 1905, and No. 13,711, A.D. 1906, comprise the use of a transformer and a current-fluctuating device in the control circuit for the purpose of releasing the check lock at the hand-lever. A special form of electric switch for use in the arrangement is described. In the operation of the points motor m, Fig. 1, the hand-lever l<11> is moved over until the slide s is stopped by the shoulder i<11> engaging the check lock i<1>. A circuit through the motor is then closed from the battery b through contacts d<11>, 11, 14, b<1>, o, lead o', coil y, motor winding m<1>, lead k<1>, to battery b, and the bye pass valve v is held closed, the circuit through its coils being from the battery b through contacts 11, 14, b<1>, b<11>, the transformer coil t, lead v<1>, coils k, valve v, and return lead k<1>. The points are then reversed, and the valve v is forced open, the circuit of its coils being broken at the contacts z, z<1>. Another circuit is then closed from the lead v<1> through a rotary make-and break wheel g and contacts y<1>, y<11>, 7, 9, the movement of the points causing the completion of the circuit. The current in the transformer winding t is thus fluctuated by the wheel g, and the consequent current in the secondary winding t<1> operates a motor r, which closes a switch r<1> in the local circuit of the check lock coil i, so that the motion of the hand-lever l<11> may be completed. The motor r rotates a hollow cone 31, Fig. 3, so that balls contained within compartments in the cone rise and move the sliding top 33 vertically to close the contacts r<1>. The armature of a coil in the motor circuit is pivoted and presses against the cone 31 to act as a brake when the motor stops. The signal 9, Fig. 2, which is controlled by the positions of the points 15 is lowered when the hand-lever l<11> is pulled right over. A circuit is then closed from the battery b through contacts b<1>, o, lead o', the closed contact u<1> of a coil u<11> (which is energized when the points are in correct position), contacts 2, 1, motor m, and the return lead k<1>. The motor operates the signal, the valve v being held closed because the circuit of its coil is closed as follows : From the battery b to contacts b<11>, transformer winding t<1>, lead v<1>, contact u, coil v, and the return lead k<1>. When the signal arm is fully lowered, a plunger rod p<11> separates the contacts 1, 2, and breaks the motor circuit. To return the signal to the danger position shown, the hand-lever l<11> is pushed back to the position l<111>, causing the contact h<11> to lie between the portions of the contacts w, b<11>, but not to touch either, while the slotted link h' still makes contact with contacts o, b<1>. The circuit of the valve coil v is broken at the contacts b<11>, w, and the lead v<1> is connected to the return lead k<1> through the rotary current-fluctuating wheel g and the contacts 3, 4, which however are only closed when the signal has returned to the danger' position. The signal 9 returns by gravity since the valve v is open, and the contacts 1, 2 are then closed, and the motor circuit is completed, so that the motor drives the wheel g. The rotation of the motor does not affect the signal 9, because the valve v is open. The signalman finally throws over the lever l<11> into its normal position after sufficient time has elapsed for the gravity return of the signal. The contacts w, b<11> are then connected, and the circuit of the transformer winding t<1> is completed and the pulsating current flows therein. The consequent current in the secondary winding t operates the motor r, which operates the switch r' and the check lock i as described in connexion with Fig. 1. The control by the points is effected by the coil u<11>, in the circuit of which are provided a switch 21 moved by the points themselves and a switch 19 operated by the points lock k<11>. To reduce the arcs at these switches 19, 21, a low-voltage current is employed in the circuit obtained from coils 20 acting as transformer windings on the coils m<1>, m<11> of the motor. The contacts 23, 25, 26, 27 are bridged by the contact 24 only in the extreme positions of the operating-lever. An alternator a driven by a motor d supplies current to the coils m<1>, m<11> through the closed circuit from the alternator a through contacts 23, 25, lead o', coils m<1>, m<1>, and the return leads h', a<1>. The consequent current in the circuit of the coils 20 energizes the relay u<11> if the contacts 19, 21 are closed, and the signal may then be lowered. The coil k is connected as shown in Fig. 1, and is employed to release the lock k<11>, which may however be released by gravity or by a spring. In a modified form, the coils 20 may be arranged on a transformer separate from the points motor, and in another form the relay u<11> may be connected directly across the leads o<1>, h<1>, in which case the coils m<1>, m<11> will act as choking-coils, although direct current may be employed. In another modification, a battery may be substituted for the alternator and may drive a direct-current transformer. In another form, shown in Fig. 9, the relay u<1> is connected to the signal wire v<1>, and is in series with the switch 21 and a coil 18 with a return lead k<1>. The coil 18 is is of higher resistance than the relay u<11>, so that an accidental high current would melt the fuse 30. The wire v<1> Fig. 2, is normally connected to earth by the relay armature u to prevent .interference by accidental currents, and the battery return wire may be earthed for the same purpose.