GB618702A - Improvements in impact wrenches - Google Patents

Abstract

618,702. Screwing- up nuts &c. AKTIEBOLAGET ATLAS DIESEL. Nov. 11, 1946, No. 33495. Convention date, Nov. 13, 1945. [Class 83 (iii)] In an impact. wrench comprising a rotary hammer engaging, by clutch teeth, an anvil from which it is disengaged on excessive torque by an axial movement, the hammer member is forced axially away from a turning member towards the anvil by independent pressure medium actuated means acting with one end surface on one member, and forming with the other member a pressure medium cylinder. As shown, the wrench is driven by a pneumatic motor within the part 2, Fig. 1, and drives a rotary member 24. The hammer member 4, which engages the anvil 5 by clutch teeth 10, 11, permitting limited relative motion, is axially movable on a stem 12 formed on the anvil, and is provided with an upward extension 31 formed with sloping faces 29, 30, Fig. 2, between which. and similar sloping faces 25, 26 on the driving member 24, balls 27, 28 are provided. The hammer is formed with a cylindrical cavity 13 in which rides a free piston 14, compressed air being supplied to the cavity through a duct 16 in the stem 12 connected to a cross-duct 17 leading to an annular groove 18 supplied by a duct 19 in the housing wall; the duct 19 leads from the main supply through an adjustable reducing valve 22 and a main control valve 26. 35 is a reversing valve for the motor. As the torque increases the inclined surfaces 25, 26 separate from the surfaces 29, 30, as shown in Fig. 3, and the hammer member rises till the teeth 10, 11 disengage; the pressure within the cavity 13 causes the teeth to engage after slight relative rotation, the anvil receiving a hammer blow. In a modification, the turning member and hammer are connected by spaced links. The turning member may also be driven electrically or mechanically.