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How to Use an Impact Wrench

By Michele M. Howard
Loosening lug nuts is easier with an impact wrench.
BartekSzewczyk/iStock/Getty Images

An impact wrench may not be thought of as a basic, everyday tool, but it can sure make quick and easy work if you need a little extra force to complete a task. Also called an air gun, an impact wrench is typically used in jobs, such as auto repair, where a high amount of torque with a minimal amount of exertion is required. Keep safety in mind while making proper use of this tool to save you time and effort.

Plug the air compressor into a power outlet. Turn it on and set the compressor's pressure regulator to 90 psi. Stretch out the air hose and remove any kinks or twists. Without attaching the wrench, run air through the hose for five to 10 seconds. This clears the hose of moisture and any accumulated dust. Turn off the compressor.

Set the trigger switch on the tool to the "off" position. If your wrench doesn't have an automatic lubricating system, add two or three drops of pneumatic tool oil into the air inlet, which is typically located at the bottom of the tool's handle. Doing this regularly, before use, helps it last longer, deliver the proper amount of torque and run more quietly.

Attach the hose to the air inlet at the bottom of the handle. Give the hose a few gentle tugs to be sure it is securely attached to the impact wrench. Attach the correct size socket to the anvil. This is the shaft that sticks out of the nose of the wrench.

Turn the speed dial, typically located at the base of the handle, to the desired torque level. Locate the directional knob, dial or lever and set it to the desired torque direction -- forward or reverse. Set the trigger switch to the "on" position.

Hold the tool firmly with your dominant hand, and place the socket over the nut you wish to loosen or tighten. Place your other hand over the housing of the wrench and squeeze the trigger. Once the nut has been tightened or loosened, release the trigger.


Things You Will Need

  • Air compressor with hose
  • Pneumatic tool oil
  • Impact sockets


  • When not in use, store your impact wrench in a dry, enclosed place.
  • If your tool doesn't have an in-line oiling system, add oil after each hour of continuous use.


  • Wear safety glasses and hearing protection when operating your impact wrench.
  • Disconnect the tool from the air compressor before attaching or removing the sockets.
  • Only use special impact sockets. Regular hand tool sockets are not designed to withstand the high torque of an impact wrench and can break, causing injury.