How to use your FB chain wear gauge
The FB chain wear gauge was primarily designed for the measurement of leaf or forklift chain wear. It may also be used to measure all chain with an imperial pitch.
It is recommended that when conducting chain inspections the user observes the requirements of The Lifting Operations and Lifting Equipment Regulations (LOLER) 1998, The Provision & Safe Use of Work Equipment Regulations (PUWER) 1998, the FLTA Technical Bulletin 02 and the BITA Guidance Notes GN15 and GN28.
Competent persons carrying out safety inspections should meet the requirements of BS EN45004:1995. Leaf chain failure, other than a sudden breakage due to operator error, shockload or overload, is normally a gradual process during which time the chain elongates as it wears. The accumulative effect of this chain wear is a significant increase in the actual pitch of the chain. This accurate device measures the chain wear and indicates the percentage elongation.
All high quality chain is manufactured to consistently tight tolerances and it is considered that the chain is worn beyond its safe service life when the nominal pitch length has been extended by 2% to 3%. At this point the fatigue life of the chain is reduced and the ultimate breaking strength is
A chain that is elongated by 2% is becoming dangerous and the competent person must determine a safe time limit for replacement. A chain that is elongated by 3% must be renewed immediately. Until the chain is renewed the equipment to which it is fitted must not be used.
It is recommended that wherever possible the chain should be cleaned and measured in situ with the chains placed under load. The recommended load equates to approximately 1% of the minimum breaking load of the chain. Without the availability of a set of check weights it is, for the purpose of putting the chain under load, normally sufficient to allow the chains to be tensioned by the weight of the carriage and forks.
It is particularly important to measure that section of chain that passes over a pulley, this being that part of the chain that wears the most as the chain articulates during normal operation. FB chain wear gauge is an accurate measuring device and has been developed to give an early indication of wear and identify potential chain failure.
||Close gauge to confirm calibration - The FB chain wear gauge has been precision manufactured and accurately toleranced. The manufacturing process includes calibration referenced back to National Calibration Standards with each unit undergoing thorough final inspection.
The instrument cannot be adjusted for calibration but it can be checked by simply closing the slide fully and reading from the 'Percentage Wear' window the accuracy to tolerance. In the unlikely event that the instrument moves out of calibration into the ± zones it will be as a result of wear to the moving components and should not, therefore, be used other than as a guide. Similarly if the 'V' jaws are damaged the instrument may not perform accurately.
||Identify the pitch - The nominal pitch of the chain must be measured over the pin centres of one of the OUTER link plates. To assist in this the instrument is provided with three separate pairs of red arrows. Utilise one of the pairs located on the edges and the centre of the gauge. Depending upon ease of access to the chain one pair will be more suitable than the others. Locate the arrows over the pin centres of the chosen outer link plate and the nominal pitch of the chain will appear in the 'Pitch' window on one side of the instrument or the other. Select and use the correct side of the gauge relevant to the measured nominal pitch as follows:
A SCALE B SCALE
3/8" 1 3/4"
Once the pitch has been determined the number of pins (n) that the chain wear is to be measured over will appear in the adjacent 'Measure over Pins' window.
||Measure the chain - Identify the section of chain that regularly runs over the pulley as this part of the chain is the most susceptible to wear. Measurements must then be made in at least three separate locations on this section. With the chain under load and using the correct scale, place one 'V' jaw of the instrument over the first pin (pin number 1) of the selected section and then extend the slide until the other 'V' jaw locates over the pin (as previously determined).
||% wear will appear in the box at 0.25% (¼%) increments
Whilst viewing the 'Percentage Wear' window ignore any readings in the 'Pitch' and 'Measure over Pins' windows.
||If the instrument shows a 2% or greater elongation the red indicator will completely fill the window and this is a warning that the chain requires replacing. A judgment must be made, by the competent person, as to the likelihood of the elongation reaching 3% before the next thorough examination. The competent person must specify a safe time limit to ensure renewal of the chain prior to the elongation reaching 3%.
||The chain wear gauge will show wear up to 4%. Any chain used for lifting with a measured elongation of 3% or more is dangerous and must be renewed immediately. Until the chain is renewed the equipment to which it is fitted must not be used.
The instrument should be kept free of oil and grease. It should be wiped clean after use and stored in the case provided.
Do not leave the gauge where it may be exposed to high temperatures and distort.