Patent GB-738249-A (GB)
Title: Improvements in or relating to latch devices
IPC: E05B65/32
Filed: 1953-11-19
Abstract: 738,249. Door latches. ENDTER, W. A. Nov. 19, 1953, No. 32155/53. Class 44. A latch mechanism comprises a supporting body e.g. a plate 13, a bolt 14 movably carried by the body and adapted to override and move by progressive latching take-up and camming action along a keeper surface, a spring 27 urging the bolt in the latching direction, a releasable dogging part 19 operatively interposed between the bolt and the plate and operable to block anti-latching movement of the bolt from latched position and means 17 operated by the keeper 12 to release the dogging part and thereby anti-latching movement of the bolt. The bolt is rotatably mounted on a pin 24 and is partially enclosed by a housing 32 ; it rigidly carries a pin 56 which projects through an aperture in the plate 13 and on the other side of the plate pivotably mounts the dogging part 19. The dogging part has a depending arm, the end of which is formed with a plurality of teeth 61 adapted to engage an ear 63 on the mounting plate under the influence of a spring 57 thus preventing antilatching movement of the bolt. The means 17 in addition to releasing the dogging part also acts as a safety catch ; it consists of a pin protruding through an aperture in the plate 13 in the path of the keeper and secured to a releasing element 18. The element 18 is pivotally mounted on a pin 35 and is urged by a spring 36 so that the pin 17 is normally at the upper part of its aperture, the keeper tending to deflect it downwardly. The pin 17 is adapted to be moved by the keeper before it is reached by the bolt when the door is moved in the closing direction. It is first moved downwardly by the keeper surfaces 22a and 22 and then moves upwardly along keeper surfaces 23, 23a and when on surface 23a acts as a safety catch as shown in Fig. 3. In its initial downward movement, it causes releasing element 18 to bear on an arm 60 of the dogging part to rotate the dogging part and move it along the side of the ear 63 so that it cannot engage the ear to prevent anti-latching movement of the bolt. The movement of the pin 17 also causes it to bear on the adjacent surface 34 of the bolt to move it in the anti-latching direction until when the pin 17 begins to move along surface 23, the bolt is directly engaged by the keeper. Further closing movement of the door causes the bolt to override the keeper and to move upwards along surface 23. This movement of the bolt eventually allows the teeth of the dogging member to successively engage the ear 63 until the door can close no further ; which particular tooth is finally engaged depends upon the degree of compression of the normal rubber door cushion. To open the door the releasing element 18 may be moved both from inside and outside the door to release the dogging part from the ear 63 and to move the bolt by means of the pin 17. The element 18 is moved from the inside of the door through a bell crank 42 which is pivoted on a flange 13a of the plate 13 and one arm 44 of which engages a projecting portion 45 of the element 18. The bell crank is connected to a handle through a link 41. The element 18 is moved from the outside of the door through a push button element 46 which turns a pivotally mounted crank 48 which has a shoulder 49 engaging an ear 39 on the element 18. The crank 48 also has an extension 50 which can be engaged by a pivotal locking member 52 to lock the crank 48 against bolt releasing movement. The member 52 is biased to both its locking and unlocking positions by an overcentre spring 53 and it is moved by a push-button 55 on the inside of the door. If the member 52 is in its locking position when the door is open, it is moved to the unlocking position during the closing of the door by the downward movement of the dogging part, the toothed part of which in such case engages the member 52.