Patent GB-410492-A (GB)
Title: Improvements relating to level crossing gates for railways and the like
IPC: B61L29/02
Filed: 1932-11-16
Abstract: 410,492. Gate fastenings. NICHOLSON, J. H., 31, Charleville Road, Dublin, ROBERTS, W. S., Newby, Ruff Lane, Ormskirk, Lancashire, and RAILWAY SIGNAL CO., Ltd., 40, Broadway, Westminster. Nov. 16, 1932, No. 32435. [Class 44.] Level crossing gates interlocked with the signals or block instruments have one gate provided with a locking mechanism from which a key can be withdrawn only after the gate has been released for opening and such key is then used to release the second gate. One form of mechanism is shown in front and side elevation in Figs. 2 and 3. To release the gates the signal levers must be at danger to permit a lever in the cabin interlocking frame to be moved over, thereby locking the signal levers against operation and lowering the slide 12 through rodding connections. The recess 15 in the slide 12 is thus brought adjacent to a barrel keylock so that the barrel 13 may now be turned 180‹ by its key 14 since the recess 15 allows entry of the circular portion of a cam 16 on the barrel 13. The slide 12 is thus locked so that the locking lever in the frame and in turn the signal levers are locked against operation. The rotation of the barrel removed the cam 16 from a recess 19 in a second slide 18 which is thus released and allows the bit 20 of the gate bolt 2 to be rotated downwards so that the bolt can be axially withdrawn by the bit 20 passing through the slot 21. The barrel 13 is now locked against rotation by a flat 17 on the cam 16 bearing against the edge of the second slide 18. The key 14 can be withdrawn in this position of the barrel lock and is used to operate a similar slide and barrel lock mechanism whereby the second gate of the crossing is released. To return to normal conditions, the above steps are carried out in reverse manner and finally the cabin locking lever is operated to free the signal levers, the slide 12 then being in the position shown so that rotation of the barrel lock cannot be effected since the flat 17 of the cam 16 bears on the edge of the slide 12. In a modification, a second barrel which is rotatable by the bolt bit and which has a recessed cam to co-operate with the cam 16 is substituted for the second slide 18. If the crossing is at some distance an electrically released lock may be used instead of the slide 12, the electric lock being energized by operating the cabin locking lever which is interlocked with the signal levers ; the cabin locking lever in turn is locked by an electric lock energized under control of the barrel lock or other mechanism of the crossing gate, and therefore the gates must be shut and locked before the signals can be cleared. Inter-locking with the block instrument is effected by providing a second key lock for the slide 12 so that a key from the block instrument must be inserted to release the slide 12. This key is released from the block instrument only after the train has passed the crossing and actuated a treadle or a short track circuit; an emergency release is provided in case the train is cancelled. Withdrawal of the key interrupts the instrument transmission line, but the bell or telephone line is maintained. The block instrument may be directly interlocked with the barrel lock. Specifications 199,891, [Class 44], and 367,451 are referred to.