Behold the Wild, Wondrous Guts of an Impact Gun

A quick look at a tool that’s invaluable to gearheads.

Youtube.com/Nick Moore

Reflect upon any garage you've visited or worked in, and the sound you're most likely to associate with it is the whir, hiss and rapid hammering sound of the impact gun. This handy little tool—which you may have seen race crews using to quickly remove and install wheels during a pit stop—is essential for any professional or home garage. It helps mechanics remove stubborn nuts and bolts (or any fasteners torqued too tight, really) without having to rely upon unwieldy levers like cheater bars where there may not be room. Plus, impact guns are much faster than hand tools. And they sound way cooler.

So what does an impact gun do? As you'll see in this video, it uses either compressed air or an electric motor to drive a small flywheel. The flywheel has tangs (metal nubs that stick out) to engage and release corresponding tangs on the shaft attached that’s driving the nut or bolt via a tough impact socket.The flywheel is connected to the power source by a large spring, allowing the tangs to disengage from one another periodically throughout every rotation. The result is a series of quick torsional hammering actions that apply a lot more force than if the twisting torque was constant.

That’s why we get to hear that familiar “DAT-DT-DT-DT-DT-DT-DT” when someone's using an impact gun. Name a garage tool that sounds cooler than that!