Tyres are among the highest cost consumable items on rubber-tyred earthmoving and mining equipment; looking after them properly is a key factor in extending tyre life.
Two broad areas affect tyre life and performance: operational factors, and maintenance practices.
Taking note of both these areas and following the recommendations outlined in this article will help ensure maximum tyre life and reduced machine downtime.
OPERATIONAL
Keeping your haul roads in good condition is a vital first step towards maximising tyre life.
Assuming you are in a position to influence haul road condition (if you`re a subbie on a project, you may not be), taking the time and effort to keep your haul roads well maintained, well graded, and free of rocks and obstacles will certainly pay off.
Here`s some haul road don`ts that will certainly add to tyre wear:
- Steep grades and sharp turns result in increased slippage, leading to faster abrasive tyre wear.
- Loose rocks or other obstacles increase tyre cutting and damage. They will also slow down haul and travel speeds.
- Poor drainage results in mud and potholes, resulting in tyre spinning, faster wear, cuts and higher fuel consumption.
Your operators can also contribute to longer tyre life. They should be instructed to:
- Avoid sharp objects or rocks, as well as puddles and muddy areas on haul roads (and to report them promptly when they occur)
- Avoid driving over berms and windrows when possible
- Avoid spinning the drive wheels (this also applies on wheel loaders when going into the pile)
- Slow down in loading areas, where rocks may have fallen off the loading tool or other trucks
- Never turn steering axle tyres unless the machine is moving; doing so causes very high stress and sheer forces within the tyres
- Promptly report mechanical problems, such as wheel misalignment, loose or broken suspension or grabbing brakes
- Inspect tyres on a daily basis as part of the pre-operating walk-around inspection (for more on what to look for, see maintenance tips below).
If your haul distances or you start hauling heavier loads increase as your project, quarry or mine develops, you will have to take into account the tonne/kilometre ratings of your tyres.
This is getting into the `black art` of tyre management, and you will be well advised to get your tyre supplier representatives involved for technical advice.
MAINTENANCE
Proper maintenance of tyres is the other key factor in extending their life - and this will be a joint responsibility between your operators and your maintenance crews.
First up, correct inflation is critical. We can`t stress too much the importance of correct inflation.
Improper inflation is the single most common cause of premature tyre removal.
Results of improper inflation include:
- Increased wear rates
- Irregular tread wear
- Reduced casing durability
- Lower fuel economy.
Both over-inflation and under-inflation cause problems.
Over-inflated tyres:
- Are more rigid and less able to withstand shocks
- Are more vulnerable to hazards that can lead to cuts, punctures and carcase breaks
- Wear faster.
Under-inflated tyres:
- Generate heat - and heat is the primary cause of premature tyre failure.
Because all tyres eventually need to have air added, under-inflation is probably the commonest problem.
First up, you`ll need to know exactly what the correct pressure for the tyre and application is, which means taking into account loads, weight distribution over axles, haul distances, etc. You should consult with your tyre supplier on this.
Tyre pressures can`t be measured by eye; it`s essential that you use a proper tyre gauge. By the time tyre pressure has dropped far enough to be obvious to the eye, it`s likely to be well under what it should be, and heat damage may have already occurred.
Tyre pressures should be checked at least weekly - and when the tyres are cold.
Here`s some other tips for keeping tyres in top condition:
- Carry out daily visual inspections, looking out for cuts, uneven wear, damage, cracks, etc. Any of these can be signs that you need to look at operational factors (haul road condition, operating practices) as well as mechanical factors (wheel alignment).
- Don`t let dry, caked mud accumulate on tyres, and remove any wedged rocks or other obstructions.
- Rotate tyres regularly and ensure they are properly aligned.
- Inspect even damaged and worn tyres; it may be possible to repair or retread them, or put them on machines with less onerous duties.
- Keep the valve caps on the valve stems. This is the cheapest and most effective protection against air loss.
- Check for leaky grease fittings. Oil and grease can cause rapid deterioration of tyres.
- Check wheel rims and flanges. If they`re bent, chipped or broken, they can damage the tyre. Rust, oil or grease on the wheels can also contribute to tyre deterioration.