How to Use an Air Impact Wrench

Impact Wrench
  • 1-5 hours
  • Beginner
  • 0-200
What You'll Need
Air impact wrench
Car wheels
Car jacks

An air impact wrench is most likely to be spotted in a mechanic's or tire shop. You will see them used regularly to change the wheels on a car. Air impact wrenches, or rattle guns, or torque guns as they are otherwise known, are a high powered socket wrench that can be used under extreme air pressure to loosen and tighten nuts. Air impact wrenches mostly operate using compressed air, which is why you are likely to hear a loud hissing sound when you see one in action. Using an air impact wrench is relatively simple.

Step 1 - Assemble

An air impact wrench looks a lot like an old fashioned drill. It has a silver metal body and a trigger release switch which allows the user to exert the right amount and level of air and torque pressure. The air impact wrench is attached to a long rubber hose, which in turn is attached to the air pressure unit that supplies the air pressure to the air impact gun. The pressure is only released when the user applies hand pressure to the trigger. Assemble the air impact gun by following any directions that come with it. The hose should be attached to the pressure unit first and then to the wrench. This leaves you free to remove the wrench from the hose at any time, using the quick release clip.

Step 2 - Testing 1, 2, 3…..

Once you have attached the hose and wrench to the pressure unit make sure the unit is exerting the right level of pressure for your wrench. PSI (Pounds per Square Inch) should ideally be set to between 90 and 100 PSI. Run a quick visual check of the hose line and make certain it is straightened out and free of any twists or kinks. Like a water hose, if there is a kink in it the water will get stuck and bulge out under the pressure. Air will do the same, so check for that before you use the wrench.

Test the direction to which the air impact wrench is set by lightly touching the trigger and seeing which way it turns. You will note a latch or knob somewhere on the side of the wrench which allows you to reverse the socket direction. If you want to loosen, make sure it faces counter-clockwise and for tightening, clockwise.

Step 3 - Speed

Assign the correct speed using the dial or switch on the wrench and set it to the correct speed for the project you are undertaking. Once you are happy that it will have the correct level of speed and torque you can attach the correct size socket to the bit on the front of the wrench. Slip the socket bit onto the wheel nut and press the trigger on the air impact wrench. The nuts of the wheel should loosen nicely and then you can take them off.