GB807602A - Improved door latch mechanism - Google Patents

Abstract

807,602. Push-pull catches. GENERAL MOTORS CORPORATION. May 8, 1957 [June 21, 1956], No. 14638/57. Class 44 A door latch mechanism comprises a slidable bolt 32 adapted to be engaged by a striker and a trip lever 41 pivotally mounted on and slidable with the bolt, the lever having a pawl 47 adapted to abut against a stop 29 to latch the bolt in a retracted position relative to an opening, an exposed end of the bolt being movable by initial engagement of the striker to further retract the bolt and thereby disengage the pawl from the stop without moving the same out of alignment therewith, continued movement of the striker effecting a pivotation of the lever so as to move the pawl out of alignment with the stop so that the bolt can thereafter slide behind the striker for holding the same in a door closed position. The bolt and trip lever are contained in a casing 12 the bolt being mounted on the casing by means of pins 34 located in elongated slots 33 of the bolt. The lower end of the bolt is wedge shaped having oppositely inclined surfaces 37 and 38 and a rearwardly projecting lobe 39 and it is urged downwardly into the opening, which is formed in the casing, by a coiled spring 28 which is mounted on a guide finger 26 formed in the casing and which engages a projection 43 on the trip lever 41. The lower end 46 of the trip lever projects into the opening when the door is closed so that the bolt is in its latching position. The striker is a roller 51 which is mounted on a plate 22 which also carries a second roller 53, the roller 51 engages the end of the bolt and the roller 53 serves as a guide and abutment in co-operation with a ledge 31 on the casing 21. The latch mechanism is normally attached to a door and the striker plate 22 to the door frame and on the closed position of the door the lobe 39 of the bolt is in engagement with the roller 51 to hold the door closed. When the door is opened by a pull on its handle the roller 51 engages the surfaces 37 of the bolt and moves it upwardly; this upward movement alloves the trip lever 41 to pivot by the pressure of the spring 28 on its projection 43 until eventually its pawl 47 is moved over the stop 29 which is a projection formed in the casing 21. Continued movement of the door so that the roller 51 passes the nose of the bolt eventually allows the bolt to move downwardly again under the pressure of the spring 28 and the pawl 47 engages the stop 29 to limit this movement. When the door is closed the roller 51 engages the surface 38 of the bolt moves the bolt upwardly slightly and when the roller moves passed the nose of the bolt it engages the trip lever 41 and swings it about its pivot so that the pawl 47 moves out of vertical alignment with the stop 29 so that the bolt can move dowwardly to its latching position. In a modification the spring 28 can be omitted in which case the weight of the lever 41 is arranged to bias the pawl 47 to cooperate with the stop 29.