GB191324193A - Improvements in Signalling and Interlocking for Railways and Tramways. - Google Patents

Abstract

24,193. McKenzie & Holland, a n d Edmonds, C. H. W. Oct. 25. Coribined electrical and mechanical systems, non-automatic. - Ahead of the section-clearing treadle controlling the releasing magnet of the lock on the block-instrument plunger, there is provided a treadle or the like controlling a relay which controls the circuit of the releasing magnet so that, after a train has been accepted, the plunger is not released if another train is shunted over the usual clearing-treadle. In the apparatus shown, a train is accepted by closing the plunger contacts 19; the line current also serving to energize a relay magnet 11. The relay armature contacts thereupon break the line circuit at 23, close a ' stick circuit ' at 12 and close at 13 the circuit of the usual clearing- treadle 4. The accepted train, in passing out of the section, closes at the treadle 4 the circuit of the lock-releasing magnet 17 and afterwards breaks at the treadle 9 the ' stick circuit ' of the relay 11. A train shunted into the section passes over the treadle 9 first and, in breaking the ' stick circuit ' of the relay 11, causes the armature to fall and the circuit of the magnet 17 to be permanently broken at 13. The armature can be reset by means of a key 28.