Fastener driving apparatus

1,060,659. Stapling machines. FASTENER CORPORATION. Nov. 25, 1963 [Dec. 21, 1962], No. 46434/63. Heading B4C. A stapling machine comprises a piston 20 for actuating a driver 22 and slidable in a cylinder 18 having an open top which is selectively placed in communication with a reservoir 16 of pressure fluid by a main control valve 54, fluid-means 88 for returning the piston from an operated position to a normal position, and control means 96 responsive to the pressure within the cylinder above the piston for selectively operating the fluid means. The cylinder 18 is slidable within a chamber 14a, 14b, the upper open end of the cylinder normally being in sealing contact with a resilient disc 54. The lower end of the cylinder is of reduced diameter and is adapted, upon downward movement, to abut a valve member 40 loaded by a spring 41 to a normally closed position shown. The control means 96 has a piston (96b, Fig. 2) communicating with the cylinder via a port 110 and with the reservoir 16 via a port 94, the piston being connected to a valve (96a) controlling the flow of compressed air from the reservoir to the underside of the piston 20 via a passage 88. A vent valve 68 is maintained in the normally open position shown, by means of compressed air fed from the reservoir via a port 86 and passages 76, 78, so as to act on a piston 60 connected to the vent valve. In operation, upon actuating a valve 28, the flow of compressed air which has been acting on the lower end of the cylinder so as to maintain its upper end in contact with the valve disc 54, is cut off thereby allowing the cylinder end to move away from the disc and thus permit the air to act on the piston 20; the downward movement of the cylinder immediately causes the valve 40 to open, thus permitting the air below the piston to escape to atmosphere. The operation of the valve 80 also causes the supply of air to the vent piston 60 to be cut-off so that the air pressure acting on top of the piston 20 also acts on the lower side of the piston 60 to close the vent valve, the piston 20 then being driven downwardly. The piston 20 remains in the lower position until the valve 80 is released, thereby causing the cylinder to rise and again abut the disc 54. Compressed air which has been acting on the piston (96b) via the port 110 is then cutoff and the latter piston is raised by pressure acting on the underside via the port 94. Air then passes through the passage 80 to raise the piston 20. A rubber buffer 50 i