GB1297591A - - Google Patents

Abstract

1297591 Impact wrenches ATLAS COPCO AB 7 Jan 1971 [14 Jan 1970] 720/71 Heading B3N A rotary impact motor comprises an anvil 19 with a hammer 34 rotatably surrounding the anvil, a peripheral groove 30 on and circumferentially around the anvil, an impact surface or surfaces 31, 32 in said groove, an impact dog 37 axially movable but non-rotatably supported in the hammer for taking impact and release positions, a radially inwardly directed follower 40 in said impact dog in engagement with the groove, the groove providing an axial cam rise for moving the follower lug to an impact position during relative movement between the hammer and the anvil, see Fig. 7, and means for providing an axial bias on the impact dog for moving it to a release position. The groove is a screw groove and the means for providing an axial power bias is an oblique groove 41 in a driving member 24 and a ball 42 which engages in the groove and a recess 39 in the impact dog. This ball also provides the driving connection between member 24 and the hammer 34. In clockwise operation after an impact of the follower against face 31 the relative positions of part of the motor are shown in Fig. 7. Further rotation of the hammer and driving member occurs with the anvil stationary. This causes ball 42 to move to the other end of groove 41 and thus cause the follower member to move in the same direction out of engagement with face 31 and into alignment with groove 30. The follower then moves along the groove for another impact. The drive for the motor is a conventional reversible pneumatic vane motor. In an alternative embodiment, Figs. 10-12, (not.shown), the groove is a ring groove having a cam crest bordered by cam surfaces and the cam follower has a cam crest bordered by cam surfaces, The groove 41 is replaced by a V-shaped ball groove.