Reaction torque sensors

Static Torque Sensors – Precise Reaction Torque Measurement Without Rotation

A static torque sensor (reaction torque sensor) measures torque in stationary or slowly moving systems where no shaft rotation occurs. Unlike rotating (dynamic) torque sensors, a static sensor is fixed to the test object and directly captures the so-called reaction torque. These sensors are ideal for applications where there is no continuous rotation, but where the force acting on a shaft or another stationary component needs to be measured.

What characterizes a Reaction Torque Sensor?

• No rotation required
  The sensor measures force transmission when the component is stationary or moving very slowly. It is typically connected to the test object via a rigid coupling or flange.
• Strain gauge (SG) technology
  High-precision measurements are usually based on bonded strain gauges, which convert mechanical deformation into electrical signals through linear resistance changes.
• Simple signal transmission
  Power supply and signal output are transmitted via cables—no complex telemetry systems are required.

How to choose the right Reaction Torque Sensor

• Measurement range & accuracy class
  Typical ranges extend from a few Nm up to tens of thousands of Nm, with accuracies as high as ±0.05% FS.
• Design & mounting
  Options include flange or square drive designs with high torsional stiffness and compact form factors (e.g., torque flange sensors).
• Environmental conditions
  Consider protection ratings (e.g., IP class for moisture), temperature influences, and external disturbances such as bending moments or lateral forces.
• Signal output & interfaces
  Options include mV/V output or integrated amplifiers, as well as digital interfaces like USB or EtherCAT if required.
• Calibration & maintenance
  For long-term accuracy, regular calibration (e.g., DAkkS-accredited) is recommended—typically on an annual basis.

Difference Between Static and Dynamic Torque Sensors

• Feature
• Static (Non-Rotating)
• Dynamic (Rotating)

Measurement

• Reaction torque, no rotation
• Torque in rotating systems (real-time)

Signal transmission

• Wired
• Slip rings or contactless telemetry

Applications

• Test benches, torque tools, calibration
• Motors, machinery, rotating systems

Measurement range

• High static torque
• High speed and varying loads

Advantages of a Reaction Torque Sensor

• Highest accuracy during slow or stationary conditions: Particularly suitable for testing and calibration scenarios
• Robust, simple installation: No slip rings or complex components; often flange-mounted for shaft support
• Low maintenance & long service life: No wear caused by moving parts; high resistance to harsh environments
• Flexible scaling: Measurement ranges from sub-Nm to 50 kNm achievable, with customised solutions

Common applications

• Test benches and calibration facilities: Reliable determination of tightening torques, reaction torques or screw force tests
• Quality assurance for screwdriving tools: Correctly set tightening torque prevents errors or damage
• Research & development: Precise data for drive or material tests, including in laboratory environments
• Automotive, aerospace and mechanical engineering: Where slow force application with high precision is required

A reaction torque sensor is the first choice when reaction torque needs to be measured precisely in non-rotating or slowly varying systems. Thanks to its robust design, high-precision strain gauge technology and simple installation, it can be used flexibly – from trade applications to high-tech industries. For applications in your test bench, laboratory or assembly process, Althen offers suitable standard and customised solutions with comprehensive consultancy and calibration services.