A torque meter is a device used to measure and record the torque on rotating systems, like engines, motors, transmissions or rotors.
Torque sensors work by applying a strain gauge to a rotating shaft. As the strain gauge deforms due to rotation, its resistance changes. The new output signal is transmitted to the tester to display the torque measurement to the operator.
Torque testers are also used to calibrate torque-controlled tools like electronic wrenches and screwdrivers. There are able to measure in both clockwise and counterclockwise directions, convert the strain gauge signal into several different engineering units, and measure both static or dynamic forces.