how worn chain wear indicator accurate easily keeps track of chain elongationBefore considering the various features and differences between the two methods it is important to note that the FB chain wear gauge was designed to specifically address the common problems previously associated with the ‘Tape/ Steel Rule’ methods that existed at the time.

FB invented their chain gauge after they studied all the other versions that were available in the market.  They noted with interest that several of these, sold and distributed by major OEMs, used measured lengths of between 12” - 15”.   FB was determined to have a design that would be robust, easy to use and accurate.

It was felt that by making the FB chain gauge user friendly the measurement process would be simple, consistent and accurate.  It was recognised that when measuring chain a compromise must be made in determining the length of chain to be measured.  Too long a length and there will be a danger of diluting the true extent of the wear and too short a length will require far greater measuring accuracy than is generally available out in the field.

FB developed their ‘Professional Chain Wear Gauge’ incorporating “V”-jaws for positive pin location, removing the necessity for estimating the position of the pin centre line.  There is strong evidence that it is rarely possible to accurately find the centre line by other ‘visual’ methods.  The FB chain gauge has a window giving a direct reading of chain wear, eliminating any need for calculation as well as removing confusion and possible error with an arithmetical calculation.

FB Chain and HSE were closely involved in the drafting of the BITA guidance note GN15 and FB, therefore, has no hesitation in recommending that "Competent Persons" should follow all the guidelines contained within it.

It is considered that the FB Professional Chain Wear Gauge is an instrument designed to fully assist the “Competent Person” by ensuring complete compliance to the GN15 process.


The following features were considered absolutely necessary for the correct measurement of chain by competent persons.

  • The chain gauge must be accurate
  • Results must be consistent and repeatable
  • The results must be clear and not require calculation
  • The chain gauge should be easy to use by Engineers as well as laymen
  • Measurement results should be easily demonstrated to end users
  • The instrument of choice must be robust and look professional

How does the FB chain gauge compare to a tape or steel rule when looking at these required features.

The chain gauge must be accurate

  • The FB chain gauge incorporates “V”-jaws for positive location in the pins.  This means that the FB chain gauge always locates on the centre of the relevant pin thereby ensuring the accuracy of the results.

Compare this to a tape or steel rule that not only requires visual line up but also a totally steady hand.

  • The percentage elongation, measured with the FB chain gauge, is directly shown in the “Percentage wear” window.  This again ensures complete clarity of the results.

Contrast this with the method required for a tape or steel rule.  Firstly there are extreme difficulties with the visual line up of a tape or rule.  Even if it is possible to hold the tape or rule steady there are added complications with known "parallax error" dependant on the position of the inspector’s eyes.

This is why people often say that to use a tape or steel rule accurately one needs to be ambidextrous, have three hands and two sets of eyes!

It is not surprising that visual errors exist with the tape or steel rule method considering that 0.25% wear is only 0.75mm over 300mm (12 inches).


Results must be consistent and repeatable

  • The positive location of the “V”-jaws used on the FB chain gauge means that the results will be consistent and repeatable.  This means that the results can be checked and demonstrated with ease.

This compares very favourably against a tape or steel rule.  Unless extremely lucky the difficulties associated with the physical line up of a tape or rule will be insurmountable and the result will be inconsistent and non repeatable.


The results must be clear and not require calculation

  • With the FB chain gauge there is no necessity to perform any type of calculation.  The percentage elongation is clearly shown in the “Percentage Wear” window.  The FB chain gauge is foolproof.

On the other hand when using a tape or steel rule the inspector will need to not only read the measurement correctly but also "do the math" to calculate the wear.  One can only imagine the errors and confusion that can arise when trying to get this calculation correct.

  • Here is a typical example of the manual calculation required when using a tape or steel rule and clearly demonstrates the difficulty that would be experienced in judging the exact percentage wear.

In this example the chain is 15.875 mm (5/8”) pitch and is measured over a length of 18 pitches.  The actual length measured was judged to be 286.7mm.  Use this formula to calculate the percentage wear:-

X= ((L- (P x N)) x 100) / L

P = pitch of chain;  N = pitches measured;  L = measured length;  X = percentage wear;

Therefore: X = ((286.7-(15.875 x 18)) x 100) / 286.7 = 0.33%

With the FB chain gauge there is no need to worry about getting this type of calculation correct and the onerous task of judging the exact measurement (to at least the nearest 0.1mm) is totally unnecessary.


The chain wear gauge should be easy to use by Engineers as well as laymen

  • Every FB chain gauge is supplied with full and comprehensive instructions on the correct use of the instrument.  These instructions show how to determine the correct pitch of the chain being measured.  They describe the process of measurement in detail and give clear guidance on the correct process to be followed.  With the ease of use of the chain gauge and the positive location on the pin ends it is equally effective whether in the hands of a skilled engineer or a complete novice.

In comparison only a skilled practitioner would have any chance of using a tape or steel rule; even without the necessity to make the correct mathematical calculation and elongation assessment.


Measurement results should be easily demonstrated to end users

  • Engineers and service managers often comment that because the FB chain gauge is so simple to use engineers are able to demonstrate, to their own customers, the full extent of the wear in the inspected chain quite openly.

This removes the suspicion traditionally associated with the whole measurement process and enhances customer relationships.  This is especially true when it is suggested to the customer that a new chain must be purchased.


The instrument of choice must be robust and look professional

  • The design, packaging and presentation of the FB chain gauge are very professional.  The gauge, the wallet and instructions all have a professional feel and carry the FB corporate theme throughout.  The gauge is not only robust but can be wiped clean after every inspection.

The FB chain gauge will enhance any toolbox and will been seen by users as the best way to accurately and consistently measure chain elongation.