An air, electric or battery impact wrench whose internal hammer and anvil deliver rapid rotary blows instead of steady torque. It breaks loose seized nuts with little reaction on the operator's arm, but its tightening torque is poorly controlled and varies with air pressure, battery charge and joint stiffness. Torque-limiting extensions or a final pass with a hand torque wrench are used where the spec matters.
Spin the lugs on with the rattle gun, then finish them by hand with the click wrench in a star pattern.
Also heard as
- impact gun
- impact wrench
- air gun
Related terms
Ugga dugga
Imitation of an impact wrench, meaning tightened by impact until it sounded done rather than to a torque spec.
Click wrench
Shop name for an adjustable torque wrench that clicks and briefly gives way when the set torque is reached.
Rounded off
Describes a hex head, nut or socket recess whose corners have worn smooth so wrenches just slip.
Hard joint
A bolted joint that goes from snug to final torque in very little rotation, typically under about 30 degrees.