Patent GB-849825-A (GB)
Title: Improvements in or relating to latch mechanisms
Inventor: KRAUSE HERBERT
IPC: E05B65/19
Filed: 1957-01-09
Abstract: 849,825. Latches. CHICAGO FORGING & MANUFACTURING CO. Jan. 9, 1957, No. 929/57. Class 44. In a latch mechanism comprising a keeper in the form of a plunger 3 adapted to penetrate an aperture 7 in a latch plate 5 and be releasably locked against withdrawal by a latch 20 mounted in the keeper and in which the keeper carries, in addition to the main latch 20 a safety latch 62 and a control lever 70 for operating both latches the main latch 20 is pivotally mounted within the keeper and has an arcuate slot 25 lying on a circle centred substantially at the pivotal mounting of the main latch and receiving a pin 30 located within the keeper, the slot having a serrated edge 26 which is positioned to engage the pin, the pivotal mounting of the main latch being so designed as to permit limited sliding movement of the main latch for the purpose of disengaging the serrated edge 26 of the slot 25 from the pin 30. In the arrangement according to Fig. 2 the latch 20 is slidably and pivotally mounted on a pin 15 fixed to a wall 13 of the plunger which also carries the pin 30. An abutment 37 on the latch 20 projects into a slot 38 in the plunger 3 and co-operates with a recessed edge 74 of the lever 70 which is pivoted about a pin 60 fixed to the plunger wall 13. The safety latch 62 is also pivoted about the pin 60 and projects through an aperture 64 in the plunger wall 11. In operation, release of the mechanism from the position shown is effected by a lifting movement of the lever 70 which causes an ear 78 thereon to engage and withdraw the safety latch 62 while the recessed edge 74 engages the abutment 37 to withdraw a flanged edge of the latch 20 through an aperture 50 in the plunger and out of engagement with the plate 5. In another arrangement, Fig. 8, a latch element 111 loaded by a relatively strong spring 113 is pivotally and slidably mounted on a pin 110 fixed to a lever arm 101 loaded by a relatively light spring 101a which is itself pivoted at 100 on a plunger 3a. A pin 115 on the arm 101 extends inwardly through a slot 120 in the latch element 111. A release arm 150 pivoted on a plate 3b and a locking portion 152 thereof is movable into and out of engagement with a slot 104 in an ear 102 of the lever arm 101. An abutment 155 carried by the lever 150 is also movable into and out of engagement with an abutment 157 on a safety latch 160. In operation, release of the mechanism from the position shown is effected by rotation of the lever 150, which brings abutments 155, 157 into engagement to release the safety latch 160 against a spring 165 and disengages the ear 152 from the ear 102 of the arm 101. Continued rotation of the lever 150 raises the plate 3b and plunger and effects unlatching movement of the element 111 against the springs 101a and 113. In the arrangement according to Fig. 12, a control arm 211 and a latch element 213 are pivotally mounted on a pin 211 fixed to a plunger 203, the latch element being similar to that of the Fig. 8 construction and being urged outwardly of the plunger by a spring 217. An integral safety latch and release lever 241 is pivoted at 240 to the plunger and includes an abutment, which, when the lever 241 is raised to release position moves out of engagement with an abutment 230 and the arm 211 and allows the latch element 213 to move to release position. In a further arrangement, Fig. 16, a latch element 312 is pivotally and slidably mounted on a supporting lever 310 against a spring 315 which itself is pivoted on a pin 309 in a plunger 300 and against a light spring 320. A pin 326 on the lever 310 projects into a slot 330 in the latch element 312. A spring loaded safety latch 340 pivoted in the plunger 300 is formed with an abutment 344 which overlies a slot 345 formed in the wall 301 of the plunger and which is engageable by an ear portion of an operating lever 350, to move the safety latch'to release position when the lever is moved upwardly. Continued movement of lever 350 moves the ear portion out of the path of movement of the lever 310 which together with the latch element 312 is free to move inwardly of the plunger 300 as the latter is moved upwardly to release position. In all arrangements, the serrated slots 25, 120, 214 and 330 respectively are such that a force tending to separate the plunger from the apertured plate in the locked condition of the mechanism is resisted by the engagement of the respective pin with its serrations which locks the latch element in latching position.