Patent GB-190409378-A (GB)
Title: Improvements in and relating to Tablet, Train Staff and like Systems and Apparatus for Working Traffic on Single Line Railways.
Filed: 1904-04-23
Granted: 1905-04-13
Abstract: 9378. Edmonds, C. H. W., and McKenzie & Holland. April 23. Controlling traffic on railways, staff and ticket systems for.-In a tablet system of the kind described in Specification No. 17,195, A.D. 1895, means are described for cutting-out and for re-opening an intermediate cabin only with the consent of the signalmen at the three cabins and when points and signals are properly set. Double-tongue relays are included, each having one polarized and one non-polarized armature. Only one-line wire between stations is required. In addition to the ordinary tablet instruments at the intermediate station B, the apparatus shown in Fig. 2 is provided for locking the keys which lock and unlock the point and signal levers at the cabin B. These keys, when inserted into the apparatus, turn the commutator switch drums KS K<1>S<1>, and are locked in by the action of the teeth on the links LG attached to the armature of the locking-coil LC ; when the coil LC is energized, the keys are free to turn, and the 'lock off' signal i is shown at a window in the case of the instrument. Two permanent magnets PM, P<1>M<1> are fixed to the back of the apparatus, and the cores of two electromagnets C, C<1> are arranged as continuations of the poles of the permanent magnets. The armatures U, U' carry insulated rods d with contact-plates c attached and signal flags J<1>, J<2>, and are normally held away from the poles by springs l, l<1>. The insertion of the key into the drum K'S' and the turning of it to the right lifts the bar RS by the pawl PW, and this bar lifts the armatures U, U' up to the pole-pieces, which retain them in that position until a current is sent through the coils U, C<1> which neutralizes the effect of the permanent magnets PM, P<1>M<1>. The contact-plates c make connections in different positions between springs G, G<a>, H, H<a>, K, K<a>, L, L<a>, M, M<a>, N, N<a>. Two relays R, R', Fig. 1, are attached to the back of the apparatus, and two tapping keys T<2>, T<3> are fitted outside the case. In addition to the ordinary tablet instruments at each cabin at the end of the line AC, an extra tablet instrument to work from one to the other AC, CA is provided, and also the instrument shown in Fig. 7. This consists of a switch drum SD, Fig. 1, with a handle SH which is also used as an indicator for the conditions of working, words being inscribed on the case indicating whether long or short sections are being worked, and the handle acting as a pointer. Locking in either position is effected by the tooth o on the lever LB engaging in notches p, p<1> on a disc mounted on the switch-drum spindle. When the magnet LM is energized, the tooth o is raised and the lock off' signal moved to the front of a window in the case of the apparatus, and the man at the cabin AC can then turn his handle to the other position. The sectors r, r<1>, pivoted to the disc and held against pins s, s<1> by springs, prevent the small notches p<2>, p<3> from catching the tooth o when the magnet is de-energized by breaking the circuit on moving the switch drum. The double-tongue relay RC, R<1>C<1> is an ordinary polarized relay with an additional unpolarizei armature 0,59 which can only be moved by a comparatively strong current, whereas a comparatively weak current moves the polarized armature. The armature O, 59 normally makes a contact in the circuit of the locking-magnet LM, so that a current for operating the tablet instruments breaks the local circuit and does not unlock the switch drum SD. A tapper key T is fixed on the instrument. The system is shown diagrammatically in Fig. 1. To cut out the intermediate station B, the operator there asks those at A and C for permission by ordinary methods, then turns his commutator switch KS by the key SS as far as it will go, and then asks the men at A and C to plunge on their round tablet instruments AB, CB. This action of the man at station A completes a circuit from the battery AY at station A, through instrument AB, lines l, l<1>, key T, line-wire L to station B, wires l<2>, l<5>, relay R to earth through switch drum KS. The action of the man at station C completes a similar circuit, and, both relays R, R' being energized together, the local circuit from battery B<4> to coils LC is complete, and. these coils then draw their armature and release the switch drum KS, enabling the man at station B to turn his switch drum KS and withdraw the key SS. Turning the switch drum breaks the circuit at the springs 8 and 9, 11 and 12, and the galvanometers of the instruments AB, CB go to zero. The man at station B then, as in the known system, uses the key SS to release his interlocking-levers, sets points and signals for long section working, and then withdrawn his long section key as described in the prior Specification. He inserts this key in the switch drum K<1>S<1> and turns it as far as possible, thereby lifting the armatures U, U' of the permanent magnets and causing red flags J<1>, J<2> to show at the windows of the case, and making contact between springs G, G<a>, and L<o>, L<a>. The man at station B asks the man at station A to hold down his tapper key T, and holds down his own key T<2>, thus completing circuit from battery B' at station B, wires l<18>, l<19>, line-wire L, wire l<21>, and relay RC to earth. The armature Q is attracted to contact R<o> and makes a local circuit through the locking-magnet LM, which draws its armature and shows the signal ' lock off' at a window, and enables the man at station A to turn his switch to "long section" working. The man at station A then turns his switch drum SD, and breaks the local circuit at the springs 4, 5, the handle becoming locked. He then gives a plunge on the instrument AC which sends a current from the battery AZ through wires l<29>, l<1>, tapper key T, line-wire L to station B, tapper key T<2>, wires l<30>, l<31>, l<32>, l<33>, coil C C, and wires l<34>, l<35> to earth at spring 36. The current in the coils C neutralizes the effect of the permanent magnet PM and the armature U falls, breaking contact between springs G, G<a> and making contact between springs H, H<a> and K, K<a> and showing a white flag at its window, indicating the completion of the operation between the stations A, B. Similar operations are gone through between stations C, B, and the line is then ready for long section working ; the circuit between the instruments AC, CA being battery AZ, wire l<29>, l<1>, key T, line-wire L, key T', wire l<30>, l<31>, l<32>, l<36>, l<37>, l<38>, l<39>, l<40>, l<41>, key T<3>, line-wire L<1>, key T', wire l<9>, l<42>, and instrument CA to earth. To return to ' short section' working, the man at staticn B first obtains permission from those at stations A, C, then turns his long section key and switch KS as far as possible. This breaks contacts 29 and 30, 31 and 32, 33 and 34, 35 and 36, 38 and 39, and makes contacts 21 and 23, 22 and 24, 25 and 27, 26 and 28. The men at stations A, C give a plunge on their instruments AC, CA, and a current passes through instrument AC, wires l<29>, l', key T, line-wire L, key T<2>, wire l<30>, l<7>, relay R, and wire l<5> to earth through spring 22. A current from station C by a similar circuit passes through relay R, and, both being energized at once, joins up the local circuit through the lock-coils LC, which then show the 'lock off' signal and enable the man at station B to turn his long section key further to the left and to withdraw it, thus breaking circuit through galvanometers at the stations A, C and also re-setting the armatures U, U<1>. He uses the long section key to release the levers for the points and signals, and also his short section key SS as described in the prior Specification. He inserts the key SS in the switch drum KS and turns it as far as possible to the right. He then asks the man at station A to hold down his key T and also holds down his own, and so completes a circuit from the battery B<1> at B through the wires l<100>, l<19>, L<20>, key T<2>, line-wire L, key T, wire l<2>, and relay coils RC to earth ; the relay coils RC are energized, and armature Q makes contact at S and completes a local circuit from the battery B' through the magnets LM and enables the switch drum SD to be turned round to ' short section,' where it is again locked. Both keys T, T<2> are then released, and the man at station A gives a plunge on his instrument AB sending a current from the battery AY through the key T, line-wire L, key T', wires l<30>, l<31>, l<102>, l<34>, coil C C, and wires l<33>, l<32> to earth at spring 19. The coils C, C neutralize the permanent magnets, and the armature U therefore drops and shows a white flag. The instruments at A and B are now joined in circuit as follows :-From battery AY to wire l, key T, line-wire L, key T<2>, wires l<2>, l<4>, and instrument at B to earth. The instruments at B and C are joined up by similar operations between B and C. The switch drums carrying contacts 37, 38, 39 may be replaced by a disc carrying contact-plates.