... and axletrees,good resistance to wearing,with high precision in dimensions,lower noise,advanced centric running castings2.without vent and highly ... H6, the holes of fittings(such as couplings, belt-pulley, sprocket wheel and so on) must properly matethe shaft ,which prevents ... breakage because of over-loose mate.1.4 Driverssuch as sprocket wheel and gear must be fitted close to bearings in ...