Patent GB-1286996-A (GB)
Title: Fastener driving tool
IPC: B25C1/04
Filed: 1969-10-21
Abstract: 1286996 Fastener driving tool FASTENER CORP 21 Oct 1969 [5 Dec 1968] 51581/69 Heading B4C A power operated fastener driving tool com-  prises a drive track 34, a reciprocable driver 32, a pusher 88 for pushing a fastener, e.g. a nail (as shown), into the drive track and movable between a retracted position (Fig. 2) and a forward position (Fig. 1), and a manually actuated control means operable to initially retract said pusher and prevent initiation of the power stroke of said driver until after the pusher is clear of the drive track. The illustrated tool is pneumatically operated, and includes a safety valve 74 comprising a valve member 112 movable from a "safety" position (Fig. 1) to an "operable" position (Fig. 2) when the movable nose 136 is pressed against a work surface, and a trigger operated valve 72. When the valve member 112 is in its "operable" position, passage 106 is not blocked, and passages 146 and 148 are in communication so as to permit pressure air from reservoir 14 to flow into bore 78 to move a feed piston 76 against bias of spring 98 and open communication between a passage 132 communicating with chamber 108 and a vent 134. Movement of the feed piston 76 to the right also retracts the pusher 88 to the Fig. 2 position. Actuation of trigger 128 raises ball 116 of valve 72 from seat 120 and into engagement with seat 118. Pressure air in chamber 54 is now exhausted to atmosphere via passages 100, 102, 106, and 132 and vent 134, and valve member 46 is raised due to differential pressure in chambers 54 and 40. The piston assembly 22 is driven on a power stroke. When the trigger 128 is released or the tool is raised from the workpiece the ball 116 or safety valve member 112 adopts the position illustrated in Fig. 1 so that pressure air flows into the chamber 54 via port 114 or port 110 to return the valve member 46 to the position shown in which position the cylinder space above the assembly 22 is connected to atmosphere via a bore in the valve member and a bore 44B and pressure air in the space 28 between piston heads 20, 24 then effects the return stroke of the piston assembly. A buffer member 56 is provided. The bore 78 is opened to atmosphere via passages 148, 150 when the tool is raised from the workpiece and the spring 98 moves the piston 76 and pusher 88 to the left, to move the next nail into the driving position. If the supply of nails is exhausted the pusher and piston 76 move further to the left (Fig. 3, not shown) and gasket 152 on the piston 76 engages seat 154 to prevent pressure air acting upon piston head 94 should the tool be moved into contact with another workpiece. (The force of air on the end of stem 80 is insufficient to overcome force of spring 98). Also when the gasket 152 engages the seat 154 piston 96 blocks communication between the passage 132 and vent 134. Thus with the piston 76 in its left most position the tool cannot perform a working or power stroke. In an alternative embodiment (Fig. 4, not shown) the tool is so arranged that it can remain in contact with a workpiece and the tool can be repeatedly operated by repeated actuation of a trigger (128).