Quarry Southern Africa May 2018 - Page 17

WINNING T he average life of a tyre for equipment on a quarry is 9 000 hours of operation. This figure, however, will be reduced substantially if the haul roads from the pit to the plant are in a poor condition. According to Pete Holman, senior consultant at Caterpillar Global Mining, the primary cause of damage to tyres used on equipment in quarries is related to poor haul road maintenance. “About 80% of all large tyres fail before they wear out. Cuts are responsible for about 45% of failures, with impacts causing nearly 30%,” says Holman. Not only maintenance of the haul roles plays a role in extending or reducing the life of tyres on a quarry; the actual design of the haul roads also has a significant impact. The best haul roads have crowned straight sections, super-elevated curves, safety berms and drainage ditches on both sides. 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. Operating at consistent speeds 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 QUARRY SA | MAY/JUNE 2018 _ 15