GB1281674A - Rotary impact wrench - Google Patents

Abstract

1281674 Impact wrenches ATLAS COPCO AB 15 June 1970 [19 June 1969] 28818/70 Heading B3N A reversible impact wrench comprises a housing 12, an anvil 14 having a radial cam 22, a hammer body 30, an impact dog 34, and a drive element 25, the impact dog is journalled in a recess 33 and has a common surface therewith of over 180 degrees, the impact dog co-operates with the cam to pivot the dog into an impact position, Fig. 4, the drive means engaging the dog, recess 26 and extension 45, for pivoting the dog to a release position. From a release position, Fig. 6 (not shown), a cam edge 43 of the impact dog follows the cam 22. When the impact dog reaches the position of Fig. 8, end surface 41 engages cam flank 37 to move the impact dog into an impact position. This impact position is maintained during impact by edge 43 engaging cam ridge 39. After impact the position is maintained during rebound and a secondary impact at which point the impact dog is pivoted to a release position by recess 26 and anvil extension 45. The radius of curvature for cam flanks 37, 38 is the same as for the impact dog recess 40. The wrench motor can be suitably powered although preferably it is a reversible pneumatic vane motor. In an alternative embodiment, Figs. 10 and 11, the cam 22 has two lobes to form the necessary cam flanks. A further embodiment, Fig. 12, has straight plane cam flanks and the recess 40 has a pair of plane impact surfaces connected to a central plane perpendicular to the central plane of symmetry of the impact dog.