Patent GB-155680-A (GB)
Title: Railway block section detector
IPC: B61L23/12
Filed: 1919-10-14
Abstract: 155,680. Roe, N. P. Oct. 14, 1919. Staff, tablet, and ticket systems; signalling-instruments.-Token or other instruments are provided with an apparatus, attached to or forming part of the instrument, which includes electromagnets controlling the circuit to the instrument relay in such a way that a wagon entering the section, when the instrument is normal, energizes a magnet which breaks down the instrument circuit and closes a bell circuit, and if a train, to which clearance has been given, arrives without the last vehicle, the relay circuit cannot be closed to give clearance to another train. In the latter case, insertion of the train token into the instrumen causes the bell to ring. A special key in a lock in the instrument may be inserted in another lock to stop the bell and enable the instrument to be used after arrival of the last vehicle. " Line clear " may be cancelled by energizing another electro-magnet when necessary. A locked switch is also provided for putting the apparatus completely out of action. Fig. 4 shows the arrangament of parts for use with a Neale's token instrument to the disk 56 of which lugs 61, 62 are fitted. A wagon blown or shunted into the section past track contacts 39 closes these contacts and energizes magnet 6 by current from battery 37 over contacts 63, 39, magnet 6, contacts 20, 29, 27. Magnet 6 moves its armature 13 and allows lever 7 to open contacts 10, 12 in the circuit of instrument relay 55 and to close contacts 8 in the circuit of the bell 5. A key may be removed from the lock 78, thereby opening contacts 79 in the relay circuit and used in lock 24 to open the contacts 28 in the bell circuit, and 29 in the circuit to magnet 6, and close contacts 26 so that as the wagon is passed out of the section over contacts 39 the magnet 23 is energized to restore the lever 7. Replacement of the key in the lock 78 resets the apparatus for normal working. The movement of the handle of the instrument to receiving position causes the cam 62 to close momentarily a circuit at contacts 72 from battery 38 to magnet 16 of the two-coil relay, the armature 14 of which is moved from its normal position, as shown, to close contacts 35 and open contacts 20, 18. On arrival of the train with the last vehicle, an attachment on that vehicle closes contact 53, which may be of the kind described in Specifica- 155,414, and energizes the magnet 15, which restores the armature 14 to normal. If, however, the last vehicle does not arrive so that the contact 53 is not closed, then the insertion of the token in the instrument closes at contacts 77 a circuit from battery 38, over wire 118, contacts 77, wire 111, magnet 6, and contacts 35, 12, 11; the magnet 6 acts as above-described to break the instrument relay circuit and ring the bell, but the instrument handle can be returned to normal position, in which it becomes looked against further operation until the last vehicle is brought in. In case of failure of the armature 14 to move when the contacts 72 are closed, the magnet 6 is energized by the closure of contacts 74, thus giving warning and putting the apparatus out of use. " Line clear " may be cancelled after the token has been replaced at the other end of the section. As the instrument handle is replaced to normal, contacts 69 in circuit with magnet 15 are momentarily closed and magnet 15 replaces the armature 14. The locking-apparatus is rendered inoperative when the instrument is set for despatching a train, by the opening of contact 63 by cam 61. A switch 4 enclosed in a locked case is arranged to put the whole apparatus out of use and allow the use of the block instrument.