MaxTT Sub70 is formulated for use in tyres running at lower speeds (>70kph). It works well on farming and agricultural equipment in areas where thorns proliferate. Enhance safety and convenience by adding the SmarTTyres Tyre Pressure Monitoring system.
Effects of temperature on OTR tyre life
Significance to Industry
The generation of heat within earthmoving tyres plays an important part in the operation of many mining companies. For some operations, the non control over this undesirable heat generation leads to premature tyre failure due to heat separation while other operations who manage tyre temperature generation suffer extensive production losses due to premature park-up of equipment.
The control of tyre temperature or TKPH (Industry standard for tyres - Tonnes per Kilometre per Hour) has traditionally occurred through management of truck TKPH. Tyre manufacturers have played an important part in developing new compounds which are more heat resistant in nature. Despite the management of tyre temperature (TKPH), efficient maintenance, monitoring strategies and developments in tyre technology, sites continue to suffer from premature failures and production losses due to extreme overheating risks. Implementing an efficient cooling strategy will result in reducing the thermal stresses to the tyre and extending the tyre life. This has been important due to the ever increasing efficiency of modern mining operations with high speed equipment and reduced waiting times within all areas of the operation.
Heat Generation
The fundamental phenomenon behind the heat generation in tyres is the friction between molecules when the rubber in the structure of the tyre is under a kinematic deformation by a continuous compression-tension or torsion. This kinematic deformation is known as the hysteresis effect. As a result of the hysteresis effect and the poor thermal conductivity of rubber, the heat generation is faster than it can be transferred into the ambient air, it gradually builds up in the tyre and reaches its maximum at the outermost ply or belt.
As the operating temperature of the tyre increases the rubber considerably loses its strength. The tyre becomes more vulnerable to malfunction from fatigue, impact, cut and heat separation. Tyre operating temperature has a significant impact on tyre life, if the tyre carcass is maintained at lower temperatures then its life can be considerably extended!!
To make it easier to understand an analogy; if you were to heat honey to 90 to 100ºC and then let it cool the honey crystallises, this is what is happening to OTR tyres when heated to critical temperatures and cooled continuously for thousands of hours, they crystallise at molecular level and become hard and brittle.
“Approximately 80% of all large tyres fail before wear due to poor maintenance and operating practices. This statistic is underscored by a recent study at a major metal mine, which indicated tyre cuts (45%) and impact damage (20%) as the largest contributing factors towards premature tyre failure.”
Tyre Heat Management
So far, there has not been any successful method of actively preventing haulage truck tyres from overheating while in use. Currently mine sites are limited to passive techniques in managing their haul truck fleet either through monitoring live TKPH levels in each truck tyre or through periodic temperature and pressure measurements. Unfortunately, these methods often have poor correlation to the actual state of the tyres and can be extremely conservative - thus leading to unnecessary losses in production. If an effective cooling method were implemented on mine sites, vehicle and tyre operation would be enhanced in a number of ways ultimately leading to increased site production.
Even a drop of 5ºC can expand the operation of haul trucks by,
- Reduce rubber wear rates in tyres (longer life)
- Improve tyre resistance to chemical damage (Hysteresis effect) physical (Impact, cuts, punctures and heat separation)
- Less downtime and thus increased productivity (tonnage hauled)
- Lowering of rolling resistance which in turn results in increased fuel economy and lower maintenance costs.
Hysteresis effect, The tyres becomes brittle and more vulnerable to malfunction, impact, cut, chunking and heat separation.
