Measurement & Calibration

Measurement and Calibration - Glossary of Terms

The following information may help in selecting the appropriate measuring device for your needs.


The precision of the instrument which can be reported in three ways.

  1. By quoting the guaranteed tolerance as a percentage of the reading or indicated value, (eg. “0.5% of Reading”).
  2. By quoting the guaranteed tolerance as a percentage of the full scale value of the instrument, (eg. 0.1% FS or 0.1% FSD).
  3. By quoting a ‘class’ of device in accordance with BS7882:2008 “Method for calibration and classification of torque measuring devices”. (See page 90).

Modes of Operation

First Peak of Torque - when a “click type” torque wrench signals that the set torque has been achieved, the applied torque will momentarily drop before climbing again. Generally the fastener stops rotating at point 1, and from a standstill, the breakaway torque to achieve further rotation of the fastener will be higher than point 3b. Only if the operator is very insensitive to the break point will the final tightening effort be incorrect.

“First Peak of Torque” mode will detect the break point of the torque wrench, not the highest torque applied.

Peak Torque - this mode of operation will record the highest torque applied. In the case of a “click type” torque wrench this may be higher than the actual break point if the wrench continues to be loaded beyond the break. Consequently, Peak Torque is more useful for calibrating devices without a break signal such as dial or electronic wrenches.

Track - this mode has no memory at all.When the load is removed the display will return to zero. Track is used for calibrating the device itself or for monitoring a fluctuating torque.


The smallest measurement interval that can be determined on the indicating device.
This applies to analogue and digital devices.

Number of Digits

Digital displays are described as having a certain number of ‘digits’ or ‘active digits’.
Half digits can be used to increase the resolution of a device without the expense of going to an additional full active digit.

Eg 1. 1000 N.m displayed on a 4 digit system would read 1000 (resolution = 1 N.m).
Eg 2. 1000 N.m displayed on a 41⁄2 digit system would read 1000.0 (resolution = 0.1 N.m). Active digits change as the torque changes. Non active digits only assist in showing the magnitude of the torque. For example, 10,000 N.m requires 5 digits to display it’s magnitude.
Eg 3. With 4 active digits (and 1 passive digit), 10,000 N.m would change in steps of 10 N.m.
Eg 4. With 41⁄2 or 5 active digits, 10,000 N.m would change in steps of 1 N.m.

Signal Processing

Electronic Circuitry falls broadly into two types, analogue and digital, with most electronic measurement systems
comprising a mixture of the two.There are also whole analogue electronic systems, but these are rare in torque measurement. Most systems start with an analogue signal.The point at which the signal is converted defines the type. Analogue systems – one in which the signal is processed before being converted to digital. Digital systems – the original analogue signal is converted to digital before processing.

Measurement & Calibration

TruCheck™ Models 3 N.m, 10 N.m

The importance of keeping your torque tools in peak calibration condition is well established. Many businesses achieve this by using a third party calibration service. However, how much more convenient would it be to perform calibration checks inhouse? Tools could be checked more frequently, immediately if a problem is suspected, and tools would not need to leave site unnecessarily.

TruCheck 10 - 350 N.m

One of the concerns in putting a torque tester into an environment where people are not calibration specialists is that incorrect selections will be made with the potential for incorrect tool setting and consequently tool failure. Norbar’s solution is to remove all choices from the operator. The TruCheck is for click type torque wrenches and comes with a single measurement unit (N.m or lbf.ft).

Professional Torque Tester (Pro-Test) : Series 2

The accuracy, ease of use and price competitiveness of the Pro-Test instrument has made it the choice of many industrial, military and automotive customers worldwide. The Pro-Test Series 2 has many features designed to make life easier and reduce the opportunities for error when calibrating torque wrenches.

Torque Screwdriver Tester (TST) : Series 2

What makes the TST genuinely versatile is the interface for an external transducer. This interface, accessed by a 2 way switch in the TST, allows the connection of any transducer from Norbar’s “SMART” range and most mV/V calibrated transducers from Norbar or other manufacturers.

Torque Tool Tester (TTT) : Series 3

The TTT shares all of the extensive features of the TST except that it has no internal transducer. Instead, the TTT offers not one but three external transducer interfaces allowing any three transducers to be simultaneously connected. Selection between the transducers is made by a rotary switch at the back of the instrument case.

T-Box XL and TDMS (Torque Data Management System)

The T-Box XL together with Norbar’s Torque Data Management System (TDMS) software provides the complete solution for torque tool calibration, data logging and data management and archiving on your PC.

Flange Mounted Transducers : FMT

Flange Mounted Transducers incorporate mounting points for securely fixing the transducer to the working surface.The transducer lead is also included and is fitted with a high quality Lemo® connector, suitable for attachment to TST and TTT instruments.

“SMART” Torque Block - STB

There are two models, STB1000 and STB3000.Transducer Lead is incorporated and is terminated in a Lemo® connector suitable for the TST and TTT.

Static Torque Transducer

The accuracy and quality of the Norbar Static Torque Transducers has made them the first choice of many calibration laboratories throughout the world.

Large Bench Stand
  • Ensures the correct mounting of Norbar’s Static Torque Transducers up to 5000 N.m (5000 lbf.ft).
  • All bench stands (except Extra Large) are machined to accept Norbar Joint Simulation Rundown Assemblies for power tool testing and calibration.