GB1357749A - Fastener driving tool - Google Patents

Abstract

1357749 Fastener driving tools FASTENER CORP 16 June 1971 [15 July 1970] 28313/71 Heading B4C A pressurized fluid operated fastener driving tool comprises a control arrangement including a safety device, a trigger operated valve and a movable device for mechanically blocking the actuation of one of the safety device and the trigger operated valve, which arrangement is such that the safety device must be operated by placing the tool against a workpiece before the trigger operated valve is actuated in order that blocking by the blocking device may be prevented and that a fastener, e.g. a nail or staple, may be driven. The tool of Figs. 1 and 2, having a movable cylinder 26 containing a fastener driving piston (not shown) movable on a working stroke and a return stroke in the manner described in Specification 929,341, comprises a chamber 54 which is connected by the control arrangement 50 to reservoir 24 and atmosphere to effect respectively the return stroke and the working stroke of the piston. With the safety device or valve 46 and trigger operated valve 48 of the control arrangement in their inoperative positions, the chamber 54 communicates with the reservoir via port 92 in safety valve stem 80, and a piston 110 of the interlock device is urged to the illustrated position (Fig. 2) against bias of spring 114 by fluid passing from the reservoir to cylinder 112 via passages 102, 94, and 113. Actuation of trigger valve 48 prior to actuation of the safety valve 46 opens cylinder 112 to atmosphere via passages 113, 94 and fluted element 108. The piston 110 thus moves under bias of spring 114 so that the smaller end of the piston engages an aperture 118 in an extension 84A of an element 84, 86 rigid with the safety valve 46 to block movement of the element on application of the tool to a work surface, and the tool remains inoperative. Actuation of the safety valve 46 first by applying the tool to a work surface removes the aperture 118 from register with cylinder 112 and bring passages 56, 80A, 94 into communication, so that upon subsequent actuation of the trigger valve 48 the chamber 54 is vented and the tool is permitted to operate to drive a fastener. In the alternative embodiment of Figs. 5 and 7 the tool has a fixed cylinder 126 housing a fastener driving piston 128, and a main control valve 140. The valve 140 when lifted from the end of cylinder by venting of chamber 154 via passage 152 permits commencement of the piston working stroke, and when the valve is returned to its illustrated position by communicating the chamber with reservoir 124, an exhaust valve is opened and the piston return stroke commences. The control arrangement 150, including a safety device 146 and a trigger valve 148, controls the communication of the chamber 154 with the reservoir and the atmosphere. An actuator 186 which normally extends beyond the nose 134 of the tool, is displaced when the tool is placed against awork surface and via a pivoted lever 180 displaces rod 176 against bias of spring 178 to permit fluid pressure biased piston 204 to move into recess 176A and out of path of trigger valve element 188. The element 188 can thus be displaced by actuation of trigger 200 against fluid pressure bias to connect passage 152 to exhaust. The tool thus operates. The reservoir is in constant communication, via passage 174 with port 198 in cylinder 190 to provide the pressure fluid bias on the piston 204 and the element 188, and with a port 196 in the cylinder to provide fluid supply to the chamber 154 when the element is in its inoperative position (Fig. 7). Actuation of the trigger, after actuation of the safety device moves the element to a position in which sealing ring 192 is between port 196 and passage 152 and the passage is open to atmosphere.