When a steel wire rope is bended over a wire sheave tensions will occur.After repeatedly bendings fatigue will arise. Exactly when this fatigue will arise depends on the sheave diameter the steel wire rope is bended over. General recommendations is the sheave diameter (measured at the bottom of the groove) = "D" - should be 16-20 times the diameter of the wire = "Ø". Also the groove at the bottom of the sheave has a big impact on the lifetime of the steel wire rope. The Blue Line recommends that the groove supports the steel wire rope at a minimum of 1/3 of the circumference (120 degrees).