GB679121A - Improvements in or relating to tools for firing projectiles into metal, concrete or the like - Google Patents

Abstract

679,121. Firing mechanisms; projectiles. STEVENS, A. H. (Portable Industries, Inc.). April 20, 1949. No. 10450/49. Classes 9 (i) and 119. [Also in Group XXII] Tool for firing pins, studs and the like fastenings into structures comprises an elongated housing 10 of aluminium or other light metal, a slidably mounted carrier 11 being guided in the housing by a peg 13 extending into a slot 12. A partition 14 secured within the housing serves as rear abutment for a coil spring 16 bearing at its front end against the carrier. Removably mounted in the carrier is a gun barrel 17 having a screw-thread 18. The forward end of the barrel may be knurled to facilitate removal and is held stationary during assembly by prongs 17<SP>1</SP> which bite into the work-structure. The barrel has a bore 19 and a counterbore 20 at the rear receiving a reversible chamber lining 21 into which is inserted a cartridge 22. The plug bears against a flange 23 on the head of a stud 24, the head having a sliding fit in the bore. After firing the cartridge, the pressure in the chamber builds up until the flange 23 is sheared off and the stud driven out. Slidably mounted in the carrier is a firing-pin 25 held retracted by a spring 27 engaging a collar 26 bearing against a hollow nut 28. Passing through the abutment 14 is a plunger 30 carrying a disc 31 against which bears a spring 32 to hold the plunger in the retracted position. Slidably mounted on the housing is a sleeve 35 attached to the plunger by screws 36 extending through slots 37. Part of the sleeve is knurled to afford a grip for the operator. The spring 16 is weaker than the spring 32, so that in operation, when the forward end of the barrel is placed against a wall and the sleeve 35 pushed forwardly the spring 16 is compressed and thereby the housing 10 moves forwardly until it contacts the wall. Further pressure on the sleeve compresses the spring 32 so that the plunger urges the firing pin against the cartridge. Accidental discharge is prevented by rotating the housing relatively to the barrel so that the peg 13 is held in an extension 41 of the slot 12. The tool cannot be discharged unless the barrel is held against a surface, since the travel of the screws 36 is limited by the slots 37. Specification 653,503 is referred to.