GB956726A - Improvements in or relating to percussion mechanisms, in particular for explosively actuated fastener driving tools - Google Patents

Abstract

956,726. Cartridge-operated fastener driving tools. SARMI S.A. Nov. 22, 1960 [Dec. 3, 1959], No. 40050/60. Heading B4C. [Also in Division F3] Relates to firing mechanisms and in particular to a firing mechanism for a cartridge-operated fastener driving tool, and to a safety device which necessitates the continuous use of both hands to permit cocking of the striker and firing of a cartridge. In one form the firing pin 9, Fig. 1, formed with a striker 9a, has a tail portion 11 slidable in a block 5. The pin 9 has opposed flat side portions 9b terminating in shoulders 9x and along which are slidable two branches of a fork 13 rigid with a slidable rod 14 having a hook 14a engaging in a notch 3a of the trigger 3. The percussion spring 17 bears at one end against a flange 9c on the pin 9 and at the other end against a movable washer 16 against which the fork 13 bears. The tail 11 of the pin 9 has an annular groove 11a adapted to be engaged by the ends of push-buttons 18, Fig. 4, subjected to the action of a spring clip or ring 19 which tends to separate them from the groove 11a If the trigger 3 is actuated without pressing in the push-buttons 18, the assembly comprising the fork 13, pin 9, spring 17 and washer 16, is free to move forwardly, the percussion spring 17 remaining uncompressed. The striker is thus not cocked and no firing ensues. To obtain percussion, it is necessary to depress with one hand the push-buttons 18 and to hold them engaged in the groove 11a while actuating the trigger with the other hand. Since the pin 9 is thus held against movement, the fork 13 and washer 16 move forwardly to compress the spring 17 as shown in Fig. 4. When the fork 13 comes into contact with the shoulders 9x, the thrust exerted on the pin 9 by the trigger 3 overcomes the force exerted on the pushbuttons 18 and the pin 9 is released and thrust forward to fire the cartridge. In another embodiment the firing mechanism is of the magnetic type and the firing pin 109, Fig. 6 (without a tail portion 11), co-operates with a bar magnet 111 formed with an annular groove 111a and slidable in a cavity in a block 105. In the absence of pressure exerted on the push-buttons 118a, Fig. 8, the elements 109 and 111 move forward as a unit with the spring 17 and no cocking occurs. When the pushbuttons are depressed as shown in Fig. 8, the magnet 111 holds the pin 109 by magnetic attraction against movement when the trigger is actuated and causes the spring 17 to be compressed. When the force of the spring 17 overcomes the magnetic attraction or when the fork 13 comes into contact with the shoulders 109x, the pin 109 is thrown forward to fire the cartridge. Specifications 901,375 and 917,121 are referred to.