Patent GB-761177-A (GB)
Title: Improvements in door latch
Inventor: MCCONNELL FRANK JOHN
IPC: E05B55/12
Filed: 1954-07-06
Abstract: 761,177. Door latches. AMERICAN HARDWARE CORPORATION. July 6, 1954, No. 19705/54. Class 44. A latch unit comprises a casing 5, a latch bolt 9 slidable in the casing from a projected to a retracted position and normally projecting from one end thereof, the latch bolt being adapted to be connected to a retractor (not shown), an auxiliary bolt 37 slidable in the casing from a projected to a retracted position, supporting means 14 fastened to the casing, a dogging member 47 slidable upon the supporting means and movable transversely to the direction of movement of the latch bolt from a first position clear of the latch bolt to a dogging position wherein depression of the latch bolt is prevented, means 40 on the. auxiliary bolt adapted to retain the dogging member in the first position when the auxiliary bolt is in projected position, means, e.g. a spring 54, for moving the dogging member into the dogging position when the auxiliary bolt is in retracted position and separate cam means 28 operable upon retraction of the latch bolt for moving the dogging member out of dogging position. The auxiliary bolt is mounted in the casing alongside the latch bolt so that when the latch bolt is in its latching position under the pressure of a spring 34 in the striker plate, the auxiliary bolt is retracted against the pressure of a spring 43 by abutment against the striker plate. The dogging member 47 is a plate which is slidably mounted to move transversely of the cam and between a cup-shaped retainer 17 fitting in the open rear end of the casing and a plate forming the supporting means 14, which is secured in slots in the casing by projecting ears; it also has ears which guide the dogging plate. The dogging plate has an aperture through which a retractor bar 12 attached to the latch bolt extends and a finger 50 projecting into this aperture engages an opening 52 in the bar 12 to dog the latch bolt when the auxiliary bolt is retracted. The means 40 on the auxiliary bolt is a shank having a notch 45 in which the end of the dogging plate is secured in the dogging position. To move the dogging finger out of the opening 52 when the retractor is moved to withdraw the latch bolt, a camming bar 23 is provided. This extends parallel to the retractor bar 12 and it is provided with ears 33 at its inner end which when the latch bolt is in its latching position are urged by a spring 31 between the two bars 12, 23 engaged by the retractor before the retractor engages ears 12a on the end of the retractor bar. The camming bar passes through the aperture in the dogging plate with the dogging finger 50 passing through a slot in it and when it is moved by the retractor the cam means which form part of the camming bar move the dogging finger to release the latch bolt so that when the ears 12a are engaged by the retractor the latch bolt can be retracted. Surfaces 29 on the camming bar are provided to hold the dogging finger 50 out of the opening 52 so that the latch bolt can move normally before the auxiliary bolt when engaged by the striking plate during closing of the door. The latch unit is intended to be secured in an axial bore in a door and to be operated by a unit secured in a transverse bore.