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
JANUARY 2018 27