MINING TYRES
Monaflex launches a new generation of tyre repair systems
Tyre repair equipment specialist Monaflex says it is continuing to invest in the development of
innovative new products with the stated simple aim of creating ever increasing value for tyre repair
operations. The new R-Type components continue to utilise heat and pressure to vulcanise repairs
and are still compatible with all tyre sizes on the market today, right up to those used on ultraclass
mining equipment. However, by using specially designed reinforced materials these
components are more durable than ever before and, with a correspondingly longer life span, repair
costs are reduced. "The extra strength of the materials is so substantial it allows the components
to be made significantly lighter with greater flexibility; making them easier to use and ship." The
Monaflex range of specialist sidewall and bead repair systems has also been expanded and now
cover sizes from 14.00-24 up to 59/80R63. Repair facilities are increasingly using specialist
sidewall and bead systems alongside their standard repair equipment to optimise turn-around
times, workshop efficiencies and cost reduction.
the wear over sustained periods of operation
becomes more clear.
Tony Cutler of OTR Global also argues that there
is another AHS tyre issue that remains unresolved,
namely tyre fire detection. “There was another
autonomous haul truck tyre fire late last year on a
Pilbara iron ore mine, with a multimillion-dollar
vehicle destroyed. Several AHS trucks have now
been damaged or lost due to tyre fires. Some fires
originated in the tyre due to a tread separation;
others were truck-initiated fires that spread to the
tyre. Irrespective of the root cause, if there is no
driver to detect a smoking tyre – or the early
stages of tyre ignition – then the resultant fire can
be almost impossible to extinguish. With the
worldwide expansion in AHS haul truck
population, and associated tyre fire risk, there is a
growing need for the development of a tyre
smoke/heat/fire monitoring system to safeguard
autonomous vehicles from tyre fire.”
Kal Tire’s Ultra Repair in focus
Kal Tire’s Ultra Repair™ technology can extend the
life of mining tyres by repairing some types and
severities of injuries that previously would not
have been considered and where the tyres would
jut have been scrapped. IM had the chance earlier
in 2020 to visit the Alfreton, UK site of Kal Tire’s
Mining Tire Group for an in-depth insight into the
system and what it can achieve. The process starts
with the inspection area, where all tyres are
inspected for the quality of casings to see if they
are worth repairing and retreading. This focusses
on the bead area for any sidewall cuts and the
treads – every mm of tread loss increases
puncture risk by up to 10% on OTR tyres. Using an
Earth Scanner machine, damage not visible to the
human eye can be located – during the visit a Tier
One 27.00R49 tyre was scanned, a size suitable
for Cat 777 trucks used in the larger UK quarries.
There are only three of these scanners in the
world, and Kal Tire has two of them, one in the UK
and one in West Africa. The scanner saves time by
rejecting unsuitable casings early on.
Back to repairs – Kal Tire of course carries out
Standard Repairs, using industry standard
methods like the REMA TIP TOP system. But Ultra
Repair takes things a stage further by using a
proprietary patch and process to repair large
damaged areas and restores the original integrity
of the tyre. The technology was developed as OTR
tyres have a very high cost so it is economic for 49
in and above sizes to carry out these types of
advanced repairs. The Ultra Repair patches are are
supplied from Kal Tire Canada and and offer the
same tensile strength as the original cable and are
designed to still flex as the tyre flexes.
The identified areas of damaged are gouged to
expose the tyre injury and remove any rust,
damaged cables etc. Then the Ultra Repair patch
can be applied and covered with extruded rubber
before the tyre has an initial building up of the
main tread rubber layers – a base compound then
tread compound, then the tyre goes for retreading
which can be done using retread moulds inflated
with nitrogen followed by an eight hour cure. The
UK site has six mould patterns. The other option is
what is called “smooth and groove” where the tyre
goes in an autoclave and is then grooved using a
machine. The choice of method depends on
practical and market issues. A moulded tyre looks
more like a “new” tyre so is often preferred for
that reason. But if the customer wants a certain
pattern that isn’t available in a mould then it isn’t
an option. Whatever method is used, a retreaded
mining tyre is generally around 60% of the cost of
a new tyre but offers 80% of the performance.
Away from the UK, Ultra Repair capability is
also being rolled out at
new sites. At Detour Lake
gold mine in Ontario, now
part of Kirkland Lake Gold,
Kal Tire is setting up a full
Ultra Repair onsite
capability, which makes
sense there due to the
large truck fleet (Cat 794
AC) and the fact the mine is
quite remote. A similar set
up is being established at
Victoria Gold’s Eagle gold mine in the Yukon which
declared commercial production on July 1, 2020
and operates a fleet of Cat 785 trucks. The
advantage is obvious at remote sites – large and
heavy mining tyres that would not previously have
been considered for repair due to the damage
being deemed unrepairable and/or the shipping of
the tyre to a repair facility removing any cost
advantage of doing it.
Alternative mining tyres
One interesting piece of news at present is the
development of air suspension wheel (ASW)
technology by Global Air Cylinder Wheels in the
US. ASW comprises an outer steel drum, onto
which are bolted polyurethane or steel tread pads,
connected via an array of nitrogen filled cylinders
and oil filled dampers to an inner steel hub fitted
with a nave that bolts directly to the vehicle hub; a
mud seal connects the outer drum with the inner
hub on both sides of the wheel. An ASW assembly
replaces the standard pneumatic tyre and wheel
assembly. The claimed advantages are life to
match that of the vehicle (apart from routine
replacement of consumable components), reduced
fuel usage due to lower rolling resistance
compared with a pneumatic tyre, no tyre change
vehicle downtime and increased safety as the risks
of tyre burst, fire or explosion are eliminated.
Tony Cutler commented on this technology: “I
would think that the big challenge for AWS will be
maintaining the integrity of the outer steel drum
and attached tread pads due to road wear, tear
and impact damage especially under high speed
operation, and of the hub attachment nave due to
lateral stress that would normally be absorbed by
deflection of the pneumatic tyre during cornering.”
ASW is currently being tested at a mine in Nevada
on a Cat 777 haul truck which is normally fitted
with six 27.00R49 tyres.
Cutler adds: “It would be interesting to see how
ASW performs on wheel loaders. ASW design
seems especially well suited to this application
which generally involves low speed operation. The
steel tread pads would assist in keeping a clean
and even floor – similar to tyre protector chains –
and AWS would be ideal for load and carry
operations and tramming, both of which can
challenge pneumatic tyres.” IM
A braking test on a Cat 777 fitted with air
suspension wheels (ASW) from Global Air
Cylinder Wheels
70 International Mining | JULY/AUGUST 2020