Torque transducers take on new applications

Edited by the Engineeringtalk editorial team Jun 28, 2002

A new concept in torque measurement from Lebow Products is opening up exciting opportunities across a broad spectrum of industries.

A new concept in torque measurement from Lebow Products is opening up exciting opportunities across a broad spectrum of industries.

From the Latin word 'torquere' meaning to twist, torque is a force to be reckoned with - and not just for tightening fasteners in automobile engines.

Simply, torque invades our everyday life and without even thinking about it, we rotate or use products that rotate, hundreds of times a day - removing a bottle cap, tightening a jar lid, turning on a tap or tuning a radio knob, mixing cake ingredients, fans and blowers, machine tools, our car - the list is endless.

The requirement for accurate and reliable torque measurement is increasing rapidly for laboratory and working industrial environment applications.

The 1700 series is a highly versatile range of contactless transducers covering measuring ranges from 0-0.1 up to 0-1500Nm.

The key to the success of these transducers is that they use a unique combination of optical and inductive technology resulting not only in high-speed data capture but also excellent long-term reliability.

Traditional torque transducers designs using slip rings have always had limitations in terms of reliability, accuracy and longevity.

Slip rings readily fail prematurely and can lift off at high rotational speeds, causing inaccurate measurements.

At low speeds, friction from the rings can adversely affect the results from low-level torque measurements.

In the 1700 series, power to the strain gauges on the rotor is transmitted through inductive coupling, while transfer of data back from the rotor is achieved through a proprietary high-speed optical link method.

Using two complete different technologies means that there is no interference between the input and output signals, while the optical transmission method is not susceptible to external influences.

There are no moving parts other than the shaft itself.

Therefore the operational life of the transducers is only limited by the bearing life and typically units are capable of running for in excess of 20000 hours.

Two options, revolution detection and angular detection, extend the capabilities of the 1700 series and remove the need for additional sensors in many applications.

This enables engineers to investigate torque trends in a variety of applications in far more detail.

The revolution detection version can be used to show how torque changes with changing speed.

In a typical application for instance, the load on an electric motor under test can be varied by means of an eddy current brake.

Both torque and speed can be measured simultaneously by the transducer and output to a computer for further analysis.

The angular detection option provides valuable data in a wide range of applications.

For example, the user can detect synchronisation disturbances and pulsed torque trends within a single rotation.

When used to measure the torque pattern from an internal combustion engine, the transducer can measure the changing torque patterns from individual cylinder ignition sequences.

This data can be used to investigate parameters such as valve timing, fuel intake and spark plug behaviour.

In the industrial environment, the revolve angle facility is used in screw fastening applications.

By defining a threshold value of torque, the screw can be turned to a specific angle.

Unlike most torque transducers, the 1700 sensor has a built-in amplifier and this significantly reduces losses caused by the transmission of low level output signals.

The 0 +/-10V output is potentially divided from the 12V supply voltage.

It can be seen that the 1700 series torque transducer offers several distinct advantages over conventional devices and the units are equally at home in either the laboratory or the industrial environment.

Applications are almost limitless and include the testing of small motors, pumps, fans and gearboxes.

Their robust, compact design and built-in amplifier ensure high quality output data and the contactless design provides excellent long-term reliability.