Quarry Southern Africa May 2018 - Page 19

WINNING to prevent undulations developing. The material should, however, not become too moist when wet, to the extent where wheels sink into the haul road, bringing the sidewalls of the tyre in contact with dirt and wear away the rubber. If there is high rolling resistance on the haul road, the tyres are not biting into the road and in effect are burning rubber off the tyre. Dust control is also required as part of the environmental management plan at quarries and usually entails regular grading and spraying or wetting of the haul road surface. Main causes of tyre damage Vista Training, a US-based company, has identified the main causes of quarry vehicle tyre damage. The most common cause is sidewall damage leading to tyre failure. This happens when trucks and earthmoving equipment gets too close to berms and high bank faces, normally on narrow haul roads where trucks operators steer to the outside edge of the road to pass trucks coming from the opposite direction. Drivers should avoid hazardous surfaces to ensure all tyres remain in working order. “The most common cause is sidewall damage leading to tyre failure.” Hazards associated with loading includes delivering material to the plant where backing up over a stockpile or other material can cause severe damage to tyres. Corners are another area where tyres can run over berms. Other hazards are associated with loading at a shovel or tipping point and can include backing up over spilled material or backing up too far until the truck's rear duals are resting upon the edge of the pit face. Running a tyre on a rutted road is identified as another hazard as it can cut the sidewall and put stress on the carcass when entering and leaving the rut. A rut will cause the tyre to wear unevenly due to surface variations. Vehicle operators should be encouraged to use different areas within the haul lane to avoid ruts as much as possible. Underinflated tyres experience significant sidewall deflection, especially when the truck is travelling with a load. The result is The design of bench and dump areas can increase tyre life and reduce spillage. The turn should be broad enough to enable to turn the equipment quickly without dry steering on loose material. QUARRY SA | MAY/JUNE 2018 _ 17