Power steering torque sensor, what is it and how does it work

Torque sensors measure the torsional force that a shaft is subjected to as it goes through the various stages of its operation, either during starting, driving or stopping. They are found in engines, generators, alternators, among other automotive components. Also called a torque transducer it provides a mechanical variation in an electrical one. That is, a twist translates into a voltage variation.

How does it work?

Torque sensors have the function of accurately measuring the torque applied to fixed or rotating parts. These sensors are located on the steering pinion. A pole wheel is mounted on the input shaft, which is connected to the steering pinion by the torsion bar. As the driver turns the steering wheel, the torsion bar also rotates, and in turn, also the magnet relative to the sensor.

In general, the sensor has elements resistant to magnetism, the resistance of which changes along with the field´s direction. The sensor measurement range from 5 Nm to 20,000 Nm (Newton meter). A mechanical angle limiter prevents the torsion bar from being overloaded when higher steering torque is applied.

Behind the operation of the torque sensor is the strain gauge or extensometer. A metal sheet that is the force transducer whose electrical resistance varies according to the applied force to convert the deformation derived from force, pressure, compression, torque, weight or stress in a change in electrical resistance that can be standardized to measure a torque.

 Sensor types

 There are basically two types of torque sensors: 

• Rotary sensors. Also called dynamic sensors, they are used in applications where torque measurement must be taken on a rotating shaft or motor. In this case, the transducer rotates in line attached to the shaft and transmits a torque signal as it rotates. Also, these sensors can be found without brushes or slip rings.

• Reaction sensors. Also called static, they are less complex and cheaper than a rotary sensor, and are used as a torque wrench calibration tool. 

Advantage 

Torque sensors have a wide variety of applications in industries such as: test platforms, assembly or bolting systems, and in the automotive industry, where they are key to driving safety. In the Sun Transmission online store you will find spare parts for power steering that your vehicle needs. Browse our website to find a wide variety of transmission valve bodies, automatic transmission parts and automatic transmission filters. In case you have questions, write to us through the contact form. We will gladly assist you!