Choosing the Right Torque Wrench

A torque wrench is a tool used to tighten bolts and nuts by applying a precise torque indicated by a manufacturer. The tightening torque of bolted connections is extremely important. If it is too low, the connections will loosen and may come off, especially when subjected to vibrations. Too high a torque means over-tightening and can result in the fasteners breaking. Your choice of torque wrench should be made based on the desired torque range, expressed in Newton meters (Nm).

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What are the different types of torque wrenches?

Paoli manual click torque wrench

There are two main types of torque wrenches: click torque wrenches and real-time torque reading wrenches.

Click torque wrenches indicate when the selected torque value has been reached. Although some of these wrenches are pre-set, the vast majority are adjustable. If so, you can set a value within the range the wrench allows.

Real-time torque reading wenches display the torque value instantly.

Two Types:

Click torque wrenches

Real-time torque reading wrenches
What are the different technologies used in torque wrenches?
Torque wrenches can be manual, electric, hydraulic, or pneumatic. Whichever technology you choose, be aware that you will need to calibrate the wrench before using it.

Manual torque wrenches

These are the most common torque wrenches.

Advantages:
- They are the cheapest.
- They are easy to use–just select the desired torque and turn the wrench fitted to the element you want to tighten until it fires.
Disadvantages:
- These wrenches are not compatible with high-tightening torques (by several hundred Nm).
Please note:
- Less expensive models are also available. In these, the cable is turned to select the desired torque. These have a scale engraved on the handle.
STEALTH hydraulic torque wrench

Electric torque wrenches and hydraulic torque wrenches

These speed up tightening.

Advantages:
- As tightening is extremely fast with these wrenches, they allow for high work rates.
- They are suitable for high torques (up to several thousand Nm), which cannot be achieved by hand-tightening.
- They allow simultaneous tightening and torque control.
Disadvantages:
- They are quite expensive.
- They are more difficult to use, especially hydraulic wrenches.
Pneumatic torque wrenches

These are the middle ground between manual wrenches and electric/hydraulic wrenches. They are commonly used in various types of workshops, particularly car workshops, where they tighten car wheels with great precision.

Advantages:
- Tightening is quick.
Disadvantages:
- They don’t allow you to reach high torques.
Please note:
- These wrenches need a compressed air source to work.
Technologies:

Manual torque wrenches

Electric and hydraulic torque wrenches

Pneumatic torque wrenches
Which torque wrench should you choose for your application?
Torque wrenches are used in all industrial sectors where bolting is required (automotive, aerospace, etc.). Here are some examples of their applications:

Tightening and loosening car wheels

Torque wrenches are widely used in the automotive sector to tighten and loosen vehicle wheels.

The tightening torque for a car wheel should be between 60 and 80 Nm with a pressure of 25 kg on the end of the wrench handle. As seen above, pneumatic torque wrenches are perfectly suited to this type of application.

Cylinder head tightening in engines

The cylinder head of an engine requires very precise tightening. It must not be too tight or too loose for the engine to work properly.

The tightening torque should be between 60 and 90 Nm.

Tightening wheel hub nuts

Wheel hub nuts also require a very precise tightening torque of between 100 and 200 Nm. With an electric torque wrench or a hydraulic torque wrench, you can achieve these torques without the risk of damaging the part.