Patent GB-191223417-A (GB)
Title: Improvements in Electrical Token Apparatus for Railways.
Inventor: BLACKALL ALFRED THOMAS
IPC: B61L23/24
Filed: 1912-10-14
Granted: 1914-01-14
Abstract: 23,417. Blackall, A. T., and Jacobs, C. M. Oct. 14. Staff, tablet, and ticket systems. - The commutator switch of a tablet instrument is rotated by a token which is inserted and withdrawn through a keyway which ensures rotation of the commutator during insertion or withdrawal of a token. An indication is given of the state of the instrument by a polarized indicator moved behind an aperture in a disk on the spindle of an auxiliary commutator. The token (Fig. 4) has a segment e of the same shape as slots d5, d6, d7, in plates d1, d2, Fig. 2, on the front of the instrument and projections d3, d4 prevent rotation of the token -until it engages the spindle b of the commutator a, which is further provided with pins g by which it is rotated with the token. To insert a token, the segment e is pushed through the slots d5, d6 on to the spindle b and then turned a half revolution in a clockwise direction, the reverse movement being prevented by a fixed stop j. The commutator a is thus reversed and the segment e brought into register with the slot d7, through which it is drawn forwards, and the token may then be dropped into the magazine h. During withdrawal of a token, the commutator must be rotated counter-clockwise, and to permit this the magnet n must be energized. Fig. 5 shows the two instruments A, B, but the ringing-circuits are omitted. To release a token from the instrument A, the key r at instrument B is depressed and current passes from earth at B over contacts 2, switch r, battery s, contact 8, contact 1 of instrument B, and line wire X to contact 1, polarized relay p, switch r, contact 2, and earth at instrument A. The relay p closes the circuit to the magnet n, which releases a lock on the commutator a and so permits withdrawal of a token and consequent rotation of the commutator. The contacts 1, 2,3, 4, 5 on each commutator serve as a reversing switch. By this arrangement the withdrawal of a token reverses the current through the magnet p which thus de-energizes the maguet n and locks the commutator. Consequently the relay p cannot again be energized by current over the abovementioned circuit to release a token until instrument A has been restored to normal by replacement of that just withdrawn or until the commutator of instrument B has been reversed by insertion of the token therein. The contacts 8, 9 are short ones only, so that releasing current can only pass when the sending instrument is in its normal or reverse positions but not in any intermediate position. Fig. 6 shows the auxiliary commutator y and the indicator z1 for showing the state of the instrument. The armature p1 of relay p closes the circuit of the magnet v to permit of movement through a half-revolution of the commutator y to close the circuit from the armature p, through contact 20 to the magnet n of the token instrument. In the normal position of the commutator y, as shown, the disk z1 is exposed through an aperture 21, or is removed therefrom according to the direction of the current through the magnet z which is in series with the magnet p. A third indication is given by the removal of the aperture 21 from the visible position.