A torque wrench is a tool used to control and apply a specific torque to a fastener such as a bolt or a nut. It is a fundamental element in general mechanics, tire changing operations and industrial maintenance & repair industries, to ensure customers' safety.
Each vehicle type has different torque specifications, set by the manufacturer, which must be respected when servicing the vehicle. Not only for the wheels, but also for any other bolted parts such as the cylinder head, a torque controlled solution must be used to tighten at the required torque.
When in the past this was not really the case, today most of the industry is well aware and is most commonly using the combination of an impact wrench and a torque wrench. However, it is still necessary to remind some key recommendations about these high precision tools:
A torque wrench is a tightening tool. It is a very sensitive and precise tightening tool, and should never been used to loosen bolts.
Handle your torque wrench as carefully as you treat a measurement instrument! The tool should always be stowed in its storage box and protected from any shock.
At the end of each day, or when it is not used, the torque wrench should be reset to the lowest value, to release the string pressure.
Only use one hand with a fluent and continuous move. Most of the torque wrenches have a mark on the handle, this is to indicate where to apply pressure.
Do not use an extension on the handle. This would impair the set value in being correctly signaled.
A torque wrench prevents but do not avoid over tightening! When the required torque is reached, the torque control system of the wrench will be "activated", and the operator will hear a clear click sound. If you hear this "click" without moving the wrench at first, it means that the application has already been over tightened. The good practice here is to start over : Loosen the bolt first, tighten with an adapted tool and finish with the torque wrench to reach the correct and safe torque.
Tool Maintenance : As a high precision tool, a torque wrench needs to be re-calibrated on a regular frequency, and it's the tool's user responsibility. At Chicago Pneumatic, we recommend a yearly tool re-calibration or every 5000 cycles, at an official service center. Not to mention that if the tool has being dropped or damaged, it must be sent to service immediately. Did you know that you can change the square drive of the torque wrench without changing the tool?