Occasionally in a workshop environment, and particularly when working on motor vehicles, the home or professional mechanic will come across a standard hexagonal nut or lug nut that’s rusted or cross-threaded and simply cannot be loosened by the application of human brute force alone. This is where a particular air tool – the impact wrench, also known as a pneumatic wrench – is invaluable.
A socket that fits over the immovable nut is attached to the end of the impact wrench in the same way as with a normal manual wrench. However, when the trigger on a compressed air impact wrench is depressed, a blast of compressed is converted into a sudden burst of high-torque rotational force. Repeated bursts of this high torque force act like a hammer (hence the term ‘impact’ wrench) on the stubborn nut, gradually breaking down the resistive element that (rust, corrosion, over-tightening etc.) that originally prevented the nut from being removed.
The obvious benefit of an air compressor driven impact wrench is that it is able to supply far greater forces for tightening or loosening stubborn nuts than could be achieved using manual power alone (and which could potentially result in injury). Care and safety is also required when using an air impact wrench due to the extreme forces involved; safety goggles should be worn during operation. Care should also be taken if using an air impact wrench to tighten a nut: the nut should be applied and slightly tightened by hand first to ensure that it is not cross-threaded and over-tightening the nut using the impact wrench should be avoided