Quarry Southern Africa May 2018 - Page 18

WINNING 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. 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. Grade is also important because it affects where the load sits on the tyres. The ideal load distribution is for 33% of the load to be in the front of the truck and 66% in the rear. The ideal grade for a quarry haul road is between 8 and 10% degrees, with low rolling resistance of 2% or less. Travelling downhill laden with a full load increases the load on the front axle, generally by the value of the gradient. A cambered haul road or banked curves will increase the load carried by the tyres on one side of the machine. Haul roads in quarries should ideally be three times the width of the widest truck, so tyres do not bump into the safety berms or drop into ditches. The design of bench and dump areas can increase tyre life and reduce spillage. The turn should be broad en ½Υ ΡΌ(Δ؁|EUIIdMπ5d½)U9€ΘΐΔΰ)•Ή…‰±”ΡΌΡΥΙΈΡ‘”•ΕΥ₯Α΅•ΉΠΕΥ₯­±δέ₯Ρ‘½ΥΠ)‘ΙδΝΡ••Ι₯Ήœ½Έ±½½Ν”΅…Ρ•Ι₯…°Έ)%Έ…‘‘₯Ρ₯½Έ°Ρ‘”΅…Ρ•Ι₯…°ΥΝ•ΡΌ‰Υ₯±Ρ‘”)ΕΥ…ΙΙ䁑…Υ°Ι½…‘́͑½Υ±‰”™₯Ή”΅…Ρ•Ι₯…±Μ)Ρ‘…Ё…Έ‰”•…Ν₯±δ½΅Α…Ρ•Έ!…Υ°Ι½…‘́…Ι”)‰Υ₯±Π₯ΈΩ…Ι₯½Ύ±…ε•Ί‰δΥΝ₯Ήœ„Ι…Ή”½˜)‘₯™™•Ι•ΉΠΝ₯锁΅…Ρ•Ι₯…°Έ%Ё͑½Υ±‰”•ΉΝΥΙ•)Ρ‘…Ёё”Ι½¬΅…Ρ•Ι₯…±ΜΥΝ•…Ι”Ή½Π½Ω•Θ΄)Ν₯镐½ΘΝ‘…ΙΐΈQ‘”΅…Ρ•Ι₯…°Ν‘½Υ±…±ΝΌ)‰”Α…­•‘½έΈ…Ή½΅Α…Ρ•½ΙΙ•Ρ±δ)ΕΥ₯Α΅•ΉΠ…ΉΡεɕ́ΥΝ•₯Έ„ΕΥ…ΙΙε₯Ήœ½Α•Ι…Ρ₯½Έ΅ΥΝЁ‰”Ι½‰ΥΝЁ•Ή½Υ ΡΌέ₯Ρ‘ΝΡ…Ή)ѽ՝ ½Ή‘₯Ρ₯½ΉΜΈ