Torque numbers can be located on almost nuts and bolts, particularly on motor vehicles with the likes of internal engine parts as well as steering components and tailshaft bolts. It is not possible to measure things like this in feet, so this is why torque wrenches were created.

Torque wrenches are designed to show when users have gotten to a certain torque specification by providing an audible click or beep noise, and in some cases the wrench will also provide tactile feedback via the handle. The torque level this feedback will be given at is something that can be changed by the operator. 

Torque wrenches are usually longer than the standard breaker bar or ratchet in order for enough leverage to be given that high torque can be reached when necessary. However there are a number of different sizes of torque wrenches that are intended for use with various applications, so how do you choose the correct size torque wrench?

Torque wrench sizes

The most common three sizes of torque wrenches that are available are the ¼ inch, the 3/8th inch and half an inch drive models. This is a reference to the size socket they will accept, but the bigger the drive the bigger the torque wrench will be for the sake of providing more leverage. 

Smaller wrenches have a tendency to go down to single digit increments but often do not have a large maximum torque setting. Users that decide to choose a larger model will have much more options for higher tension, although these models are unlikely to be able to be used with smaller items of machinery. 


Torque wrenches should come with a locking mechanism that ensures that the settings will not be moved while they are in use, so operators need to unlock this to begin with. 

Once you know what your desired torque setting is, the handle of the wrench should be twisted until its edge is able to line up with the desired value. The zero should be aligned with the centre line and the handle then turned until the required single digit has been reached. There will be different increments for different torque wrenches, particularly when they are of different sizes.


After all the numbers have been set up on your torque wrench, regardless of its size, the next step will be to tighten a fastener. The torque wrench’s ratcheting function can be used to quickly tighten the fastener, as is the case with any ratchet, but under no circumstances should torque wrenches be used to try to loosen fasteners. 

When the fastener has been tightened, steady and even pressure should be applied until you hear a click from the torque wrench. Gentle pressure can then be applied until a few more clicks have been heard to make sure the right tension has been reached. 

Torque wrenches should be returned to a neutral setting after use to relieve tension within the internal spring.

Torque wrenches are vital to do a professional job but it also vital to ensure you choose the correct size torque wrench for the task at hand. 

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