Patent ID: 7918286

Claim:
An impact tool comprising: a spindle disposed in a housing and configured to be rotated by a motor; an anvil disposed in front of the spindle and rotatably supported in the housing in a manner coaxial with the spindle, a front end of the anvil protruding from a front side of the housing; an impact mechanism comprising a hammer engageable with the anvil at its advanced position, and a coil spring, and configured to transmit a rotation of the spindle as a rotary impact force to the anvil, the hammer being fitted onto the spindle at a front side portion of the spindle and rotatable along with the spindle via rolling elements while being allowed to move in a front-and-rear direction with a predetermined stroke length, and the coil spring being positioned between a large-diameter portion at a rear side of the spindle and the hammer so as to urge the hammer toward the advanced position; a restricting portion protruding from a front surface of the large-diameter portion of the spindle, and configured to receive a rear end of the coil spring and to restrict an inner diameter of the rear end of the coil spring; and a ring-shaped groove formed at a rear surface of the hammer, and configured to receive a front end of the coil spring such that the front end of the coil spring is loosely fitted into the ring-shaped groove, so as to restrict an inner diameter of the front end of the coil spring, in a manner which provides an inner cylindrical portion at a rear side of the hammer, wherein a run-off portion having a depth defined by a protrusion of the restricting portion is formed in the restricting portion so as to allow the inner cylindrical portion of the hammer to move thereinto, so that the hammer can move backward for a distance corresponding to the depth of the run-off portion.