Patent GB-348972-A (GB)
IPC: B61L19/14
Filed: 1930-08-15
Abstract: 348,972. Interlocking machines for railway signals. GENERAL RAILWAY SIGNAL CO., Rochester, New York, U.S.A.-Assignees of Howe, W. K. ; 333, Oxford Street, Rochester, New York, U.S.A.) Aug. 15, 1930, No. 24524. Convention date, Aug. 26, 1929. [Class 105.] An indication latch mechanism for a locking frame having sliding levers is arranged so that the mechanism for a lever controlling two sets of apparatus, such as the two ends of a crossover, only occupies the same space as a single mechanism; the latch mechanisms are made easily detachable from the locking frame. The parts are arranged so that there is little force on the pivoted members. Fig. 1 shows a single indication latch mechanism IL applied to a lever L; the mechanism rests on a part of the locking frame 5 at the front, and is supported at the back by a plate 78 and secured by a spring-pressed wedge D, both plate and wedge being carried by a bolt fixed in the frame ; the spring ensures uniform stresses on the parts throughout the locking frame. Fig. 2 shows the mechanism detached from the looking frame ; Fig. 3 is a section on line 3-3 of Fig. 2. The parts are enclosed between two fixed frame members 7, 8, Fig. 3, of which the member 7 is not shown in Figs. 1 and 2. The parts moved directly by the lever comprise an actuating cam member 9, which has a projection 9<1> engaging with a slot 6 in the lever L, and a detaining cam member 10 ; the two cam members are rigidly connected by a plate 11 (not shown in Fig. 2). A detent 20, sliding in vertical guides in the member 8, has a pivoted latch 21 passing through it. One arm of a spring-biased pivoted pawl 23 engages with a safety dog 27, which slides vertically. in the member 8 and has a projection 27a at the top exactly similar to a projection 23a on the arm of the pawl 23. A link 40, connected to the armature of the indication magnet IM, Fig. 1, engages with the dog 27, to lift it to the position shown, when the indication magnet is energized. A plate 34 holds the detent 20, latch 21, pawl 23, and dog 27 against the frame member 8. When the lever is moved to the left, the detent 20 is forced down by the cam surface 9a, the pawl 23 is forced down by the cam surface 9b to hold down the latch 21 and detent 20, and the dog 27 is also forced down, with the pawl 23, to prevent movement of the lever beyond the reverse indication position by engaging the stop surface 10c of the detaining cam member 10. When the indication magnet is energized, by the completion of the operation of the apparatus controlled by the lever, the dog 27 is raised clear of the cam member 10 ; the dog also moves the pawl 23 to free the latch 21, and the stroke of the lever can be completed, the detent 20 being raised by the cam surface 10a. The pawl 23 is held clear of the latch 21, against the action of the spring, by a spring-pressed ball 31, Fig. 3, engaging a depression in the member 8. If the indication magnet remains energized, the lever cannot be moved towards normal beyond the reverse indication position, since the link 40 engages the surface 10f. The operation of the mechanism during the return of the lever to normal is exactly similar to that for the reverse movement described above. The lever can always be moved from one indication position to the other except when the indication magnet is energized, in which case the link 40 engages one of the stop surfaces 10e, 10f of the cam member 10. The parts are duplicated in the double indication latch mechanism, of which Fig. 8 is a section corresponding to Fig. 3, to form two separate mechanisms, one on each side of the plate 11, which engages with the lever and carries the cam members 9, 10 ; the parts are exactly similar to those of the single indication mechanism, and corresponding parts in Figs. 3 and 8 are numbered similarly. The two frame members 7, 8 are similar to one another in the double indication mechanism: the two indication magnets are arranged one below the other.