Working Mechanism of an Impact Wrench

how does an impact wrench work

Impact wrenches are also known as the impact guns which are considered as the most powerful handheld power tools. Car mechanics widely use this tool to tighten and to undo tire’s lug nuts. Impact wrenches are there when no other wrench can make the task done when the lug nuts are so stripped that a regular wrench can’t provide proper grip or wounded too tightly.

The modern air impact wrenches can simplify this issue. If you want to know the working mechanism of impact wrenches, this article is for you. It covers the uses of an impact wrench and how does it work. So, keep your eyes glued!

What is an impact wrench?

When the other wrenches fail to get a task done, impact wrenches are there. As said before, impact wrenches are such powerful tools that are able to tighten or loosen large bolts, rusted fasteners, and lug nuts. According to the working mechanism of an impact wrench, they are able to provide high rotational torque like an impact driver. In other words, impact wrenches are the upgraded version of impact drivers.

Uses of an Impact wrench

Automotive industries are the most common uses impact wrenches. Automotive engineers use this power tool for removing lug nuts while replacing car tires. No doubt, impact wrenches are the must-have tool in the vehicle repairing shop arsenal. Another wide use of impact wrenches is in large construction projects. They come in different sizes and shapes.

How Does an Impact Wrench Works

Before you know the working principle of impact wrenches, try to get the basic. What will you do when loosening a stubborn nut or a frozen bolt using a hand wrench? The force applied by hand may not be enough to break the nut loose. But what if you hit the wrench by a hammer? The nut will definitely break loose. Right? This is the exact mechanism an impact wrenches use.

Compressed air or electric motors are used to empower impact wrenches to drive the rotor. The hammer inside is driven by the rotor in-turn.
This is the hammer mechanism that made impact wrenches special.

The output shaft is empowered by the driving motor power which is transferred if there is no resistance. But when the output shaft faces resistance, the hammer may slip from the engaging pin which leads to a higher velocity rotation and requires higher energy. This rotation connects the output shaft and the kinetic energy is transferred from the hammer to the output shaft. And this results in a higher torque on the output shaft.

The resistance may happen again if the energy blow is consumed by the output shaft. This may lead the hammer to slip and start rotating. This makes impact wrenches so powerful.

Types of impact wrenches

Considering the power source, impact wrenches have two types. Impact wrenches come with power sources- electricity and compressed air. The two basic types of electrically powered impact wrenches are corded impact wrenches and the cordless impact wrenches.

Corded Impact Wrench

Corded impact wrenches are the electrically powered impact wrenches that require to be plugged into an electricity socket. An electric motor is equipped to the rear end of the tool drives to transfer the motion to the output shaft.
These impact wrenches provide better control of speed and torque and they are easy to carry but overheating and being more expensive are the dark sides of this type of impact wrenches.

Cordless Impact Wrench

In spite of being battery powered, cordless impact wrenches have advantages over any other type. It’s higher portability allows you to carry this tool wherever you want. This type can be used in tight work-spaces. The dark sides are these impact wrenches are more expensive and continuous use on rusted nuts may drain the battery fast. So, using Li-ion batteries is recommended to recharge after use.

Pneumatic Impact Wrench

Automobile workshops are the most common users of this type of compressed air powered impact wrenches. These impact wrenches are popular among automotive mechanics because they are less expensive, more durable, and the air acts as a cooler. The dark sides are they demand compressed air supply and provides less control over torque and speed.


Hopefully, this article has helped you with the working mechanism of an impact wrench and the types of it. Using safety equipment is recommended to use these power tools.

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I’m an ex-salesman who turned a pool specialist on a very special occasion (I would disclose someday). Currently, I run my own concern as a full-time pool specialist with extensive experience and understanding of pool settings, health, and facilities. The past decade has taught me a lot about aquatics and its correlation with swimming and backyard pools. I study a lot on the development of the way we build, clean, and maintain a pool for home owners, resorts, and other parties. I can’ wait to share what I know, and I chose this blog to help me spread my insights. I hope you would find some nice ideas from my blog posts!


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