Torque Testing Overview
There are different torque testing systems and equipments in the market for the broad range of functional torque testing and measuring applications. Applications include automotive steering, drivetrain component testing and assembly, seat testing, bearing preload testing and torque-to-turn testing. The following is the typical torque testing for certain applications
Torque Testing: Bearing
The first test is to measure the breakaway torque as the outer race is held and the inner race is turned. When the bearing is rotating, the average torque is measured over several rotations.
Torque Testing: Seat Latch
The first task in the process is to perform a break-in function by exercising the part through its full motion a predetermined number of times. After the break-in the part is rotated through its full motion (one time) to measure the maximum and minimum torque values. The seat latch is then moved to the ship position.
Torque Testing: Gear Train
The resistance torque of the gear train is measured by driving and measuring the torque on the input shaft. Then the backlash throughout the gear travel is measured on the fly.
Torque Testing: Door hinge
The door hinge is first exercised in both directions and the peak torque is captured and stored. Then based on the peak torque measured, the spring tension is adjusted to increase or decrease the amount of torque needed to rotate the hinge over the detent.
Before torque testing: What is Torque?
A torque (τ) in physics, also called a moment (of force), is a pseudo-vector that measures the tendency of a force to rotate an object about some axis (center). The magnitude of a torque is defined as the product of a force and the length of the lever arm (radius). Just as a force is a push or a pull, a torque can be thought of as a twist.
The SI unit for torque is the newton meter (N m). In U.S. customary units, it is measured in foot pounds (ft•lbf) (also known as 'pound feet'). The symbol for torque is τ, the Greek letter tau.
Before torque testing: Machine torque
Torque is part of the basic specification of an engine: the power output of an engine is expressed as its torque multiplied by its rotational speed of the axis. Internal-combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,000–6,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer, and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
Understanding the relationship between torque, power and engine speed is vital in automotive engineering, concerned as it is with transmitting power from the engine through the drive train to the wheels. Power is typically a function of torque and engine speed. The gearing of the drive train must be chosen appropriately to make the most of the motor's torque characteristics.
Steam engines and electric motors tend to produce maximum torque close to zero rpm, with the torque diminishing as rotational speed rises (due to increasing friction and other constraints). Therefore, these types of engines usually have quite different types of drivetrains from internal combustion engines.
Torque is also the easiest way to explain mechanical advantage in just about every simple machine.
Authors:
Xiang Yi Power Testing Instruments Ltd provides different kinds of
torque meters and
engine testing system
