Pneumatic Impact Wrench In Coimbatore | GMS Engineering Product Description Elephant Series Akari 1/2" Impact Wrench A power tool for removing or tightening lug nuts, big bolts, and frozen or rusty fasteners is an impact wrench. They deliver a tremendous amount of rotational torque that a typical power driver can't match. Impact wrenches accomplish this by transferring kinetic energy to the output shaft via an internal pounding mechanism.