impact wrench
An impact wrench is a gun-shaped power tool designed to tighten any fasteners to any machinery, as tight as they can be. An impact wrench can perform more efficiently than a socket wrench by being commonly powered either by compressed air or electricity. It operates by rapidly rotating a mass to store energy and then suddenly delivering it to its output shaft.
Impact wrenches are used in a wide variety of industries, such as automotive repair, heavy equipment maintenance, product assembly, and construction. They're a standard equipment of race car pit crews, and allow them to rapidly switch out the car's tires in less than 20 seconds.
Impact wrenches are also called impactors, impact guns, air wrenches, or air guns.