MAINTENANCE
Leon Louw
Retreading old tyres is a good strategy to get the most from a tyre and adds several years to tyre life.
“ We have carbon black running through our veins,” says Andre Lewies, group support manager of Kal Tire southern Africa. Lewies, Wehmeyer, and John Martin, incumbent vice-president of Kal Tire southern Africa, share more than 60 years of tyre industry experience between them. All three of them emphasise the importance of proper maintenance and using the correct tyre for the correct( specific) application.
Importance of tyres
“ Tyres are one of the most important aspects of a mining operation,” says Wehmeyer.
“ The correct application— in other words, what tyre fits onto which equipment— is one of the biggest cost savers a mine can ask for,” adds Wehmeyer. With that, Lewies says the monitoring of tyres and tracking each individual tyre, whether on surface or underground, are both critical.“ Most operations get it wrong in the way that they apply a tyre to an unsuitable application. If you look at the value of the asset— and we need to regard the tyre as an asset— it must be managed as an asset,” says Lewies.
Together with diesel and maintenance expenses, tyres account for the biggest operational cost on a mine. Therefore, the maintenance of tyres is non-negotiable. Proper maintenance starts with monitoring tyre pressure— without pressure there is no tyre. The biggest loss at a mine begins with improperly executed maintenance.
“ Air pressure maintenance, especially on surface mines, is crucial. Where mining operations are focused purely on production, they often neglect to undertake proper maintenance,” says Lewies. A mine first starts to incur losses when tyres are run on the incorrect air pressures and, as a result, tyre sidewalls become damaged, cracked, or cut because of a lack of proper maintenance.
“ Good practice,” says Wehmeyer,“ is to check the air pressure every day— in some cases even twice a day: in the morning and in the evening. Worst practice is to do it once a week.” A 100-tonne rigid dump truck( RDT), for example, should run at a cold-air pressure
of 800kPa. When a tyre works, heat builds up inside it so the pressure increases. Lewies advises that when the pressure is measured, the hot pressure must be converted to recommended cold pressure. If a truck has been in operation for 24 hours, for example, the pressure would be close to 920kPa, indicating a pressure build-up of more than 20 %. At this point, the air pressure needs to be adjusted, as the pressure should rise to a maximum of 20 % as a result of heat build-up. When checking the air pressure after the truck has worked, 20 % must be deducted from the air pressure reading to indicate the true coldtyre pressure.
Lewies gives a rundown of what a proper tyre inspection in the morning should entail:“ If it is a surface mine, you need to check the air pressure, then do a check of the tyre itself, including the condition. Check for cuts and identify possible preventive repairs. The tyre needs to be removed if it is cut on the sidewall or on the thread. It is important to remove the tyre before the damage gets worse and to repair it as soon as possible.
“ When replacing the tyre,” he continues,“ do an inspection of the rim and determine whether all the components are there; make sure the rim and all the components are in a good condition. It is important to examine the nuts and studs— this is often not done by the mechanics. If there are broken studs or nuts, it can easily result in the loss of an entire wheel, with
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