Broken steering shaft

[Roger Fairclough]

"One picture is worth 10,000 words".

Looking at the state of the metal, the original fracture is obviously very old, possibly as old as the car and might possibly be the result of heat treatment. The recent cold spell could have further reduced the strength to breaking point.

Roger

 

[claires]

We were thinking the same - that the rusty part had been done a long time ago - maybe years - and the shiny bit was my break. When you say stress failures what would you think would have caused it? I havent hit anything or done anything out of the ordinary and the 'final straw' was just turning round to go out of the feed supply yard but it was before the cold weather really started. Roger, What heat treatment might that be?
thanks
claire:-}

 

[Roger Fairclough]

The part that has sheared is the sector shaft. The working part of this shaft is within the gear housing. The surfaces are subject to wear and need case hardening to prevent it but the external part ie the lower part of the shaft that is outside of the gear housing is not case hardened because it would be counter productive to the job it has to do. The break is at the junction of the case hardening and any variation in the process could begin a stress fracture that would---in this case---lead to failure.

Roger

 

[claires]

Thanks Roger - so this is a defect at manufacturer that might affect more than one vehicle? Thats a bit worrying!!

 

[frank rabbets]

Hi Claires
Stresses occur in the shaft everytime you use the stearing and yours failed in 2 stages. 1. Rusty part probably impact damage or a manufacturing crack. 2. Shiny part just because the amount of metal left could not stand the stress of everyday use for very long.

Frank............ Good luck with the new one!!

 

[Roger Fairclough]

Thanks Roger - so this is a defect at manufacturer that might affect more than one vehicle? Thats a bit worrying!!

Highly unlikely. Defects like this are extremely rare.

Roger

 

[claires]

thanks - just unlucky then I guess :-{