Torque sensor

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A torque sensor or torque transducer is a device for measuring the torque on a rotating system such as an engine crankshaft or a bicycle crank. Static torque is relatively easy to measure; dynamic torque is not, since it generally requires transfer of some effect (electric or magnetic) from the shaft being measured to a static system.

One way of achieving this is to condition the shaft with a series of permanent magnetic domains. The magnetic characteristics of these will vary according to the applied torque, and thus can be measured using non-contact sensors.

Commonly torque sensors or torque transducers use strain gages applied to a rotating shaft. With this method a means to power the strain gage bridge is necessary as well as a means to get the signal from the shaft. This can be accomplished using slip rings, wireless telemetry, or rotary transformers. Newer types of torque transducers add conditioning electronics and an A/D converter to the rotating shaft. Stator electronics then read the digital signal and convert it to a high-level analog output signal, such as +/-10VDC.