Catastrophic Steering box failure!

The pictures in the Argentinian thread are classic fatigue. Basically that shaft was cracked for a long time before the cracks grew big enough to finally break it. The crack started at that radius and grew with each movement of the steering wheel. It's possible to estimate the cycles to failure if you find a good enough microscope.
Many universities with mechanical engineering courses will have students looking for fracture mechanics studies. Something like this is ideal.

https://www.aulro.com/afvb/

Post up a pic of the fracture surface when you get it out. You'll be able to see how little was actually holding on when it finally let go.

There are two ways to inspect for this type of damage before it breaks. One is strip it and crack test. The other is a controlled overload. If it survives the overload test then it's good for another burst.

Jeeeesssuuuuuuussssssss!!

Glad you are ok. Certainly wearing the brown pants after that!

Glad you are ok Tony, not a nice thing to have happen. Was it your fence you took out as well (just to add insult to injury) or someone else's?

TimJ.

very cheap new one here:

LAND ROVER DISCOVERY DEFENDER RANGE ROVER BRAND NEW STEERING BOX WOW WHAT A DEAL | eBay

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Originally Posted by Timj

Glad you are ok Tony, not a nice thing to have happen. Was it your fence you took out as well (just to add insult to injury) or someone else's?

TimJ.

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Thanks Tim,
was not my fence:o I'm in strife over the fence, what is it with some people? I couldn't help it.:confused: Received a letter of demand today from the owner asking for compensation as a result to damages. Problem is, I know how much fences cost.:angel:

Anyway, I'll leave my battle at that.

You know what really shook me up, the fact I had my daughter in the vehicle about 20kms before the failure and there is a down hill stretch of road that cambers left just before a concrete bridge. There is no chance we would have survived with over 2 tons pushing from behind if it had let go there.

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Originally Posted by Dougal

The pictures in the Argentinian thread are classic fatigue. Basically that shaft was cracked for a long time before the cracks grew big enough to finally break it. The crack started at that radius and grew with each movement of the steering wheel. It's possible to estimate the cycles to failure if you find a good enough microscope.
Many universities with mechanical engineering courses will have students looking for fracture mechanics studies. Something like this is ideal.

http://www.aulro.com/afvb/attachment...imensionar.jpg

Post up a pic of the fracture surface when you get it out. You'll be able to see how little was actually holding on when it finally let go.

There are two ways to inspect for this type of damage before it breaks. One is strip it and crack test. The other is a controlled overload. If it survives the overload test then it's good for another burst.

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Just out of curiosity, I thought that fatigue would've showed with more rusting in the older cracks. In the above pic there is only that small section on the right hand piece at 9o'clock.

Is it that the shinier sections have polished against each other? It seems pretty clear that the pucker was the last bit to hold.

Looks like I'd save some coin if I could wait. One of those things I suppose, I need the new box asap so have already purchased one fairly local and will be in transit on monday. You pay a premium for quick parts at times. I have no issue with that. long as I make this thing safer. Far as heavy use modified vehicles go anyway.

Think once this thing is dead I should go into an esybog for the extreme use. I need the clearance and larger tyres here.;)

I was driving a Hino truck outside Newcastle a few years back when the air bias valve failed causing the air to stay confined in the brake system holding the brakes off,if it happened a half hour earlier I would have been in traffic near the Hexam bridge doing 80 without brakes.These things happen and thats the way it is. Pat

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Originally Posted by abaddonxi

Just out of curiosity, I thought that fatigue would've showed with more rusting in the older cracks. In the above pic there is only that small section on the right hand piece at 9o'clock.

Is it that the shinier sections have polished against each other? It seems pretty clear that the pucker was the last bit to hold.

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I would not have thought you would get much rusting in the interior of a steering box - it is submerged in oil.

John

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Originally Posted by JDNSW

I would not have thought you would get much rusting in the interior of a steering box - it is submerged in oil.

John

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Wish I'd thought of that.