GB1201476A - Fastener driving tool - Google Patents

Abstract

1,201,476. Fastener driving tool. FASTENER CORP. 3 Nov., 1967 [19 Dec., 1966], No. 50049/67. Heading B4C. A pneumatically-actuated tool for driving fasteners comprises a piston 26 movable in a cylinder 18 by means of compressed air fed from a reservoir 16 under the control of a valve 20, a piston return reservoir 76, a first sealing ring 86 located in a groove 82 in the piston and a second sealing ring 92 located in a groove 84 and normally adapted to seal a number of ports 90 but arranged to move away from the ports so as to admit air into the return reservoir at the end of the driving stroke when the air pressure in the cylinder reaches a predetermined value. The valve 20 includes a diaphragm 40 connected to a hollow stem 50 arranged to co-operate with a valve seat 54. In use, with a trigger-actuated ball valve 64 in the position shown, air from the reservoir 16 flows via a passage 48 and acts on the diaphragm so as to maintain it in contact with open top of the cylinder. Upon operating the trigger, the air flowing to the upper surface of the diaphragm is cut off thereby allowing the latter to be raised so that the air can act on the piston and thereby effect a working stroke. At the end of the stroke the piston abuts a rubber buffer 96 and when the air pressure acting on the sealing ring 92, via the ports 90, reaches a certain value, the air flow to the underside of the piston to raise it after the trigger is released. The piston is retained in its upper position by means of the sealing ring 86 engaging a shoulder 18d formed in the cylinder.