MAINTENANCE
Most vehicles are wide and need a
lot of space, both to drive and turn.
HAUL ROADS
PREVENT BLOWOUTS
By Nicolaas C. Steenkamp | All photos by Leon Louw
One of the biggest operational expenses of a trackless fleet on a mine relates to damage and
replacement of tyres. Haul road design and maintenance is essential to optimise operations.
T
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he average life of a tyre for
equipment on a mine is in the
order of 9 000 hours of operation,
but this can be significantly
reduced due to bad haul road conditions,
mostly due to poor maintenance. Pete
Holman, senior consultant in Caterpillar
Global Mining, says that about 80% of
all large tyres fail before they wear out.
“Cuts are responsible for about 45% of all
failures, with impacts causing nearly 30% of
premature failures,” says Holman. on both sides. However, the layout of the
mine will determine the feasibility of such
a design. Another aspect to consider is the
type of material used to construct the haul
road, such as in-situ compaction of material
or tipping and compaction of production or
plant waste and the size of the fines. The
profile of the haul roads, such as length,
width, camber and elevation of curves
and gradients has a considerable effect on
dynamic overloading and on tyre scrub.
Well-designed haul roads also increase fuel
efficiency and operator safety.
Best haul road designs
The best designs of a haul road have
crowned straight sections, super-elevated
curves, safety berms and drainage ditches Safety considerations
The contact between the tyre and the road
is the most important consideration for
both safety and even wear, the larger the
MARCH 2020
area of contact, the better. Super-elevation
is the difference in height between the
inside and outside edges of the bed of a
banked road. Properly designed, super-
elevation keeps loads level and square on
the tyres, decreasing side forces on the tyre
casing, and reducing scuffing and wear on
the treads and allows trucks to operate at
more consistent speeds, which means less
braking and less heat generation.
As anyone that has ever driven a steep
pass can attest, the grade of the road
is one of the first features that can be
physically felt by the driver. Grade is also
important as it affects the load distribution
on the tyres. The ideal load distribution is
for 33% of the load to be at the front of the
vehicle and 66 % to be at the rear. The ideal
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