GB1306144A - - Google Patents

Abstract

1306144 Fastener driving tools D HAUBOLD [trading as DIETER HAUBOLD INDUSTRIELLE NAGELGERATE] 16 Feb 1970 [15 Feb 1969] 7364/70 Heading B4C A control valve assembly in a pneumatically actuated fastener driving device including a driving piston reciprocable in a cylinder is such that the piston will perform repeated working strokes whilst a trigger (not shown) is actuated. The assembly alternately couples a passage 5, communicating with the cylinder, with an air supply line 3 and vent passage 26. Actuation of the trigger raises a hollow stem 12 (see Fig. 3) to permit air from the line 3 to pass via bores 22, 46, and 36 and valve member 45 which has been raised from its seat and act on the bottom surface of a differential piston 31. The piston is raised from its collar stop 49 to permit air to act on the bottom surface of a valve member 4. The piston and valve member 4 thus move upwardly together. A sealing ring 18 on contacting a surface 21 of housing 10 interrupts communication between the passages 5 and 26, and further movement of the piston and valve member 4 opens communication between the supply line 3 and passage 5 (see Fig. 3) thus permitting the driving piston to be driven on a working stroke. Simultaneously air passes via ports 52 and annular passage 48 into chamber 43 and the piston 31 is forced downwardly relative to the valve member 4 to open chamber 35 to the vent passage 26 (Fig. 3). Venting of chamber 35 results in the valve member 4 and piston 31 being returned to their initial positions (Fig. 1) thus closing communication between the supply line 3 and passage 5 and reconnecting passages 5 and 26 to permit the driving piston to perform a return stroke. The annular passage 48 and chamber 43 are vented via a check valve comprising a sealing ring 56 when the piston 31 has contacted its stop 49 and the valve member 4 continues its downward movement towards a buffer 53. If the trigger continues to be actuated a further cycle of operations of the valve assembly will commence. The speed of upward movement of the valve member 4 can be varied by adjustment of a screw controlled throttle needle 47.