How Can We Help You?
Find answers to the most commonly asked questions about torque products and calibration. Please contact us directly if you don’t see your question or information here.
A Torquemeter (also called a Torque Sensor or a Torque Transducer) is a device that converts mechanical torsion into an electrical signal. A Reaction Sensor measures static torque, while a Rotary Sensor handles both static and dynamic torques. The most accurate and reliable Torquemeters use multiple strain gages for sensing torque while cancelling extraneous loads and temperature effects. A more complete discussion can be found in Application Note 20171020.
A torquemeter’s overload rating is the maximum torque that can be applied without yielding its element or otherwise producing a permanent change in its performance. Overload is usually specified as a percentage of full scale.
The overload region should be reserved for unexpected events; it is not intended for frequent or continued operation. S. Himmelstein and Company torquemeters are designed for infinite fatigue life provided they are operated at or below one-half their Overload Rating. Operation at higher torques won't damage the unit, but frequent operation in that region will reduce the sensors fatigue life and may ultimately result in a fatigue failure. Operation beyond the Overload Rating can yield the strain gages or the torsion element.
A Torquemeter’s electrical Cverrange is the maximum signal that can be output with a Combined Error ≤0.1% of Full Scale. It is expressed as a percent of Full Scale. Most sensors and data acquisition systems can handle 10 V signals without degradation. However, they can't handle larger signals without clipping, severe distortion and reading errors. In other words they have little or no Overrange. Modern Himmelstein sensors and signal conditioners have substantial Overrange to handle inevitable torsional peaks and transient events. See Application Note 20805B for more information.
Full-scale is the maximum load under which the Torque Sensor is guaranteed to meet its' published specifications.
The most common English Torque Units of Measure are ozf-in, lbf-in, lbf-ft. Most common SI Torque Units of Measure are mNm, Nm, kNm. Modern Himmelstein microprocessor based sensors offer 10 or more Units of Measure that are selectable without the need to re-scale or re-calibrate the Torquemeter.
(ozf-in = ounce force - inch; lbf-in = pound force - inch; etc.)
1 Nm = 8.8508 lbf-in
To convert Nm to lbf-in, multiply by 8.8508
1 Nm = 8.8508 lbf-in
To convert lbf-in to Nm, divide by 8.8508
Dynamic torque refers to the instantaneous torque on a rotating driveline. For more information, please read our document entitled Dynamic Torque Measurement.
Torque is considered static when there is no rotation.
Nonlinearity is a sensors output deviation from a specified reference line over the sensors’ operating range. It is normally expressed as a percentage of full scale. The reference line can be determined in different ways which will produce different Noinlinearity results. It is critical to understand which reference line is used when comparing linearity specifications amongst different suppliers. For additional information, please see Technical Memo 230104B.
Hysteresis is defined as the greatest difference between the ascending and descending sensor output values. It is expressed as a percentage of full scale.
Torsional resonance, or torsional vibration, is the fluctuation in rotational speed and torque which peaks at one or more shaft speeds. When a drive system has rotating inertias and springs, it will have one or more Torsional Resonance which can cause significant, even destructive, torque multiplication. While of concern in all shaft systems, measurement and control of torsional resonance is especially important in preventing failures in power transmission systems. See Technical Memo 8150 for more information.
Use a Torquemeter(s) that has been calibrated in a facility accredited by an internationally recognized agency such as NVLAP or A2LA. Even if a torquemeter is correctly calibrated, digital field re-scaling does not transfer the accredited calibration to the re-scaled range(s). An accredited calibration must be done on every range used to be assured of accurate, traceable and certifiable measurements.
To learn more about our superior calibration services, please view our Calibration Services page.
Himmelstein calibrations include 10 ascending and 10 descending load points in both the CW and CCW directions. Then the Torquemeters Best Fit Line (BFL) is determined using all data points. The Torquemeters maximum deviation from that line, expressed as a percent of full scale, is its Combined Error. That Combined Error includes the effects of nonliinearity, hysteresis and non-return to the first load point.