PORTABLE IMPACT WRENCH

A portable impact wrench wherein a crank assembly reciprocates a cylinder which propels an impeller against the rear end of a tool holder in response to each of its forward strokes. The tool holder is rotatable stepwise in a single direction by a group of three sleeves the first of which is rotatable on but moves lengthwise with the cylinder and is normally held against rotation by a claw clutch one element of which is fixed to the housing. An intermediate sleeve has inclined teeth or threads meshing with complementary threads or teeth of the first sleeve so that the intermediate sleeve rotates back and forth in response to rearward and forward movements of the first sleeve. A third sleeve is rotatable in the housing and is connected with the intermediate sleeve by a one-way clutch. The tool holder is movable axially in but shares all angular movements of the third sleeve. Another element of the claw clutch is biased against the fixed element by a helical spring and has axially parallel teeth mating with complementary teeth of the first sleeve so that the latter can move axially but is normally held against rotation. The bias of the spring may be changed, terminated and/or assisted by a projection which can be manipulated by hand so that the user can apply his muscle power in order to increase the resistance of the other clutch element to disengagement from the fixed clutch element when the tool holder resists rotation with the third sleeve. When the claw clutch is disengaged and the cylinder continues to move forwardly and rearwardly, the intermediate sleeve rotates the first sleeve.