I think, according to the general information, that the reason is due to the following: corrosion, wear, overload and fatigue.

I think, according to the general information, that the reason is due to the following: corrosion, wear, overload and fatigue.

Several factors come to play. Cardinal amongst them is the one cited by Prof. Isam

Wear can be occassioned or aggravated when the protective parking of the shaft is compromised and strange materials like sand find inlets onto the shaft. This affects the shaft

Interesting.

Thank you my colleague Adewale Ajayi

Great contributions! it usually wears out after a period of time. Turning your steering wheel 360 degrees all the time can cause it wear out faster.