Patent GB-330242-A (GB)
Title: Improvements in mortise latches or locks
IPC: E05B55/00
Filed: 1929-03-01
Abstract: 330,242. Evans, J. W. March 1, 1929. Latches, sliding; reversible locks and latches; sliding bolts.-A mortice latch or lock comprises a case in two parts a, b, to one of which the boltapertured end-plate g is riveted, a plate p to which the latch head q is attached and the tail of which is bifurcated to provide arms y closely embracing the boss of a two-armed follower c, the arms of which engage upturned ends z of the arms y, the plate p also being apertured or cut away to house means operated by an inside handle 6 for blocking the latch-bolt or operating a separate bolt. As shown in Figs. 1, 2, 4, 6 the parts a, b have meeting flanges, whilst the part a has lugs i entering recesses in the flange of part b, and carries a distance pin e and internally threaded stud l which receives a screw, not shown, for holding the two parts together. Fig. 2 shows a locking plate n loosely pivoted on stud l to have limited endlong play. A compression spring w surrounds a rod v supported in lugs u, 2 on plates p, n respectively, and serves both to shoot the bolt and retain plate n in its raised or lowered position by passing over the dead-centre and by urging plate n towards the right so that the spindle 5 of knob 6 attached to plate n and passing through a slot o in casing member a and through a slot in the door engages behind a central projection o<1> formed on one edge of slot o. Plate n is guided by a headed stud m engaging a slot 3. When plate n is raised the latch is free for operation in the usual way by inside and outside handles on a spindle d passing through the boss of the follower c, a nose 7 on plate n limiting inward movement of the latch. When plate n is lowered an upstanding lug 8 thereon engages a bent-up tongue 9 on plate p to retain the latch against withdrawal. A plate k is provided on the door to mask the slot in the door &c. Fig. 4 shows a modification in which the plate n is operated by a rotatable knob the spindle 14 of which carries a cranked arm 12 the end 13 of which engages an eccentrically disposed slot 11. Slot 11 is duplicated at 11<a> for alternative use with crank 12 when the lock is reversed. The latch is shot by a spring 15 mounted on stud l one arm engaging a pin 18 on plate p and the other arm engaging a fixed pin 17 projecting through a slot 16 in the plate. Fig. 6 shows an alternative arrangement in which plate p has a circular aperture 20 with diametrically disposed projections 22, 23. An arm 19 on rotatable spindle 14 blocks the latch when resting on projection 23 as shown, and frees it when resting on projection 22. The arm 19 may be disposed to work in the other half of aperture 20 when the lock is reversed. Further arrangements are described in which blocking means for the latch bolt are omitted and a separate locking bolt is provided. In one form the locking bolt is shot by a follower carried on a handle-operated spindle and in another the spindle carries a toothed sector engaging a rack formed on the edge of the bolt. In both cases the plate of the latch bolt is cut away laterally to accommodate the lock bolt-operating means. The locking bolt may be retained against accidental movement by a spring friction washer around the spindle in compression between the face plate of the lock case and the follower &c. boss, or by a plate spring on the case engaging against one side or other of a hump on a flange formed on the edge of the locking bolt plate. Fig. 11 shows a latchbolt shot by springs 43 housed in apertures in plate p, and a locking bolt 36 normally retracted by a spring 41 and shot by a transversely movable wedge device 38 acting on the end of the bolt.