Torque Wrench

Click-type wrenches release with a click when the set torque is reached; beam and digital types show the value directly. Wheel nuts, cylinder head bolts, spark plugs, suspension bolts and drain plugs all have specified torques in service information. Many modern bolts are tightened to a torque value followed by an additional angle, which needs an angle gauge.

A calibrated spring or electronic sensor measures the twisting force applied to the fastener and signals when the target is reached.

Over-tightening can stretch bolts, strip threads or crack parts; under-tightening can let parts come loose. Click-type wrenches should be stored at their lowest setting and checked for accuracy at intervals, and they should not be used to loosen bolts.