Material hardness

It directly affects the wear speed and the appearance of surface damage. We can summarize that the hardness of the pinion / roller should be about 15 kg higher than that of the girth gear / tire (40 to 50HB). The number of pinion cycle being 6 to 10 times higher, it should be harder to cover the wear gap. Even with this difference, pinion always wears out faster because its specific sliding is often higher than that of the girth gear.