GB633024A - Improvements in locks, latches and like fastening devices - Google Patents

Abstract

633,024. Latches. DIMMOCK, I. Aug. 27, 1947, No. 23764. [Class 44] In a door or like latch as in Specification 511,158 wherein a catch in the form of a bellcrank lever pivoted about an axis parallel with and near to the edge of one of the door members so that at either extreme position one arm will lie within the body of that member and the other will project outwardly, a spring-urged movable abutment is held retracted from the bell-crank lever, and on pivotal movement of the latter during closing of the door the abutment is released, attains momentum, and then strikes one arm of the bell-crank to force it against the retaining stop on the other door member. A pair of supports 27, 28, Fig. 1, near the edge of the door, form the mounting for a bell-crank lever 24, Fig. 7, and a detent 39. An abutment in the form of a main bolt 29, urged into the shot position by a number of parallel tension springs 38, is housed between two metal strips 30, which being screwed to a connecting bar 31, move as a unit and constitute a security latch bolt. When the door is open, a tension spring 66 forces the arm 26 of the bell-crank to project, a spring 42 urges a claw 40 on the detent into a recess in the main bolt 29 to keep the latter withdrawn, and a compression spring 33 housed between an abutment 34 on the back plate, and a member 35 on the upper strip 30, projects the security latch. On closing side door the security latch rides over and snaps behind a pair of wedge-shaped members 62, Fig. 8, the arm 26 strikes a trip member 64, located between members 62, causing the bellcrank to rotate clockwise, and a comer contacts a projection 44 on the detent 39. The detent is consequently rotated to release the main bolt, which attains considerable momentum before striking the second arm 25 of the bell-crank, to force it against its retaining stop 63. To release the lock, a handle 50 on spindle 49 is rotated, and a follower 47 engages a projection 46 on the security latch 30. This releases the main bolt 29, which has extensions 32 contacting the security latch. A wedge 68 attached to the door, engages a wedge-shaped recess 69 in the door post, to locate the lock correctly with respect to the retaining stop. In a modification, Fig. 3, the bellcrank and detent are integral thus avoiding -lost motion between them. A pin 72, in a slot 73 in the main bolt, is engaged by a claw until the bellcrank is rotated into the position shown in chain lines. In a further modification, Fig. 14 (not shown), the bell-crank and detent are connected by gears. A modified method of projecting the bolt is described, in which a coil spring housed in a slot in the bolt acts between an end of the slot and a fixed abutment.