Abstract: The invention relates to impact wrenches for tightening threaded joints comprising an impact clutch accommodated in a housing and having a hammer which is axially movable for imparting each blow, and a device for automatically limiting the number of blows to a pre-set number of blows. The device for automatically limiting the number of blows comprises a blow number setter, a movable member directly co-operating with the hammer and axially movable upon each axial displacement of the hammer so as to enable the axial displacement of the hammer until a pre-set number of blows are delivered, and a locking device for locking the movable member against displacement in the position preventing further axial movement of the hammer after the ultimate blow of the pre-set number of blows is delivered. Thus the possibility of imparting blows in excess is eliminated without deenergization of the impact wrench drive, and the construction of the impact wrench is simplified.

Abstract: A rotary tool having a working part and a shank. The working part is formed by at least two axial portions of which the first portion is made with the profile of a twist drill for making a pilot hole, and the second portion is disposed axially between the first portion and the shank. The second portion is made in such a manner as to enlarge the pilot hole upon entering it and to ensure self-feed of the tool in the axial direction. This permits substantial reduction of required force for axial feed of the tool, improves productivity and allows making holes of different diameter with one and the same tool.

Abstract: An impact wrench that may be used in various industries for tightening threaded fasteners. In the impact wrench, a hammer and an anvil are coaxially mounted in a space relationship and axially movable with respect to each other. The impact wrench is provided with a device for effecting said relative axial movement of the hammer and anvil for engagement of their impact jaws, and a device for interaction of the hammer and anvil prior to the engagement of their impact jaws.In the impact wrench, the hammer and anvil jaws are engaged over the entire height, whereby the wear of the jaws is considerably reduced, the energy of a single blow is increased, vibration as lowered and torque tightening is ensured.