Patent GB-1047589-A (GB)
Title: A door latch
IPC: E05B63/22
Filed: 1963-11-04
Abstract: 1,047,589. Latch fastenings. PRES-PUL LOCK CO. Ltd. Nov. 4, 1963 [Nov. 14, 1962], No. 43401/63. Heading E2A. A door latch includes a casing 3 adapted for attachment to a door; a latch bolt comprising a catch 8 rigidly associated with and projecting from one end of a mounting member 9 and slidably movable relative to the casing in the direction of projection and retraction of the catch and swingable in directions transversely to the catch extending and retracting direction; resilient means 17 biasing the latch bolt in the direction of projection of the catch, for the catch to extend with a portion thereof through one end of the casing; stop means 20 limiting the extent of projection of the catch; a manually operated bar 13 axially located transversely through the casing and axially slidable in the casing; knobs 15 on the ends of the bar; a stop 30 on the bar engageable with the casing for limiting the movement of the bar in one direction to one of two alternative positions; a compression spring 16 on the bar biasing the bar to said one alternative position and when compressed acting as a stop for limiting movement of said bar to the other alternative position; a passage 23 across a portion of the bar disposed within the casing; a part 21 of the mounting member enterable through said passage when in alignment therewith for retracting movement of the latch bolt; a striker 34 having substantially convergent side faces for fixing on a door frame and adapted for swinging of the latch bolt in the transverse directions and for effecting catch retraction by a wedging action on opening and closing of the door; a transverse face of the mounting member engageable with the bar when the part of the mounting member is not in alignment with the passage for blocking retraction of the latch bolt the alignment being attained by manually displacing the bar to one of the alternative positions against the action of the bar biasing spring on opening the door while the latch bolt is swung in one direction by pressure between the catch and one of the faces of the striker whereas on closing the door the part of the mounting member is aligned with the passage when the latter is in the position maintained by the spring of the bar by swinging of the latch bolt in opposite transverse directions when striking the other face of the striker. In the construction shown the passage 23 in the bar is a groove and the part 21 of the mounting member is a tongue. The spring 16 which biases the bar is trapped between the stop 30 on the bar and an escutcheon plate 14. The casing is provided with two screw threaded portions 29 in one of which a screw 28 is engaged to act as a stop to movement of the mounting member in one transverse direction the screw maintaining the mounting member substantially central in the casing; in the other transverse direction, movement of the mounting member is limited by its coming into contact with the other portion 29 of the casing. A key actuated bolt 40 is provided in the casing which when in a projected position engages behind a tongue 22 of the mounting member to prevent retraction of the mounting member and hence of the catch 8. The stop means 20 is a lug of the casing which engages an aperture 18 in the mounting member. In a modification the helical spring 17 shown is replaced by a slightly bent wire spring, one end of which is fastened to the casing and the other end of which engages an outwardly directed loop-like embossment formed in the mounting member; this spring serves not only to maintain the catch 8 in its extended position but also maintains the mounting member centrally between the side walls of the casing. The extension of the catch is limited by a shoulder of the mounting member coming into contact with the front wall of the casing. In this construction also the spring 16 surrounds a sleeve-like extension of one of the knobs instead of directly surrounding the bar 13. In a further construction which also uses a slightly bent wire spring to maintain the latch bolt in its extended position and centrally between the side walls of the casing the part which engages the passage in the bar 13 is pin-like and the passage is a hole in the bar. The bar is grooved longitudinally so that the pin-like part remains in the groove and the hole extends from the groove. In all constructions the catch is curved on both side faces so that it can easily be swung by engagement with the striker. The latch can be used for both right and left hand doors and although shown as a mortice latch can be modified to be a rim latch.