What is torque Measurement

Torque measurement is the process of quantifying the “twisting force” that causes an object (like a shaft, bolt, or wheel) to rotate about an axis. It is a fundamental parameter in mechanics, machinery, and test systems.

Basic idea

Torque itself is defined as the product of a force and the perpendicular distance from the axis of rotation to the line of action of that force, often written as \tau = F \times r \times \sin(\theta). In simple terms, when a wrench is used to turn a bolt, the torque depends on how hard is pushed and how long the wrench is.

Units of torque

In the SI system, torque is measured in newton‑metres (N·m), meaning one newton of force applied at one metre from the axis produces one newton‑metre of torque. Other common units include pound‑feet (lb‑ft) and inch‑pounds (in‑lb) in industrial and automotive applications.

What torque measurement means

Torque measurement is the act of determining this rotational force using instruments, either directly or indirectly, for example on rotating shafts, motors, or bolted joints. It is crucial for evaluating performance, efficiency, and safety in engines, drives, pumps, and many other mechanical systems.

How torque is measured in practice

Modern torque measurement often uses torque sensors (torque transducers) that convert applied torque into an electrical signal, typically using strain gauges bonded to a shaft or flexure. As torque twists the sensor slightly, the strain gauges change resistance in a Wheatstone bridge circuit, generating a voltage proportional to torque.

Types of torque and sensors

Commonly, a distinction is made between static (reaction) torque, where the shaft does not rotate, and dynamic or rotary torque, where the shaft is spinning. Correspondingly, there are reaction torque sensors (for non‑rotating applications) and rotary torque sensors (mounted on rotating shafts in drivetrains and

test rigs).

Reaction Torque Sensor