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Old 09 August 2005, 07:29   #21
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Quote:
Originally Posted by codprawn
Obviously the casing - as I said it all depends on the design. Remember - unless a bearing is siezed there shouldn't be much force on it unless it is a thrust bearing.
Wrong, sorry mate. In turning the drive through 90 degrees you will get stresses induced by the power transfer. The secondary (driven) bevel gear in the case of an outboard gearbox is stressed downwards and backwards. Remember the difference between crank rated power and prop rated power? Thats where the missing (approx) 5% goes.

For finishing a weld on aluminium I'd recommend a grinder flapwheel-lots less stress on the weld for a start but it makes a much smoother job on the 1st use as well. I use them for any weld dressing I do now.
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Old 09 August 2005, 07:56   #22
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Lots of "interesting" views on what causes weld failure... any one of you experts want to have aguess at what caused this weld to fail? Its 13mm thick 304H s/steel, by the way....
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Old 09 August 2005, 08:08   #23
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Weld failure

Looks like it wasn't welded properly or there was a defect in the weld at the point I've circled-but there's no obvious stress cracking there or crack progression so I'm unsure. That's firebricks on the plate isn't it? Someone's not been cooling the plate down with water have they? Rapid Expansion/contraction will cause what 's happened there but it's rather corroded so it's hard to tell-much easier with a freshly failed weld. It's hard to tell if I'm not there in person either.
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Old 09 August 2005, 08:24   #24
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Originally Posted by Nos4r2
Looks like it wasn't welded properly or there was a defect in the weld at the point I've circled-but there's no obvious stress cracking there or crack progression so I'm unsure. That's firebricks on the plate isn't it? Someone's not been cooling the plate down with water have they? Rapid Expansion/contraction will cause what 's happened there but it's rather corroded so it's hard to tell-much easier with a freshly failed weld. It's hard to tell if I'm not there in person either.

I am taking the p**s somewhat, as it's impossible to tell by picture, descriptions etc, which was rather my point.. but I'll give you some more information and see what you come up with... the weld was 100% radiographed at manufacture.... the equipment runs in the high 700's (centigrade)... The cooling rate when it comes off stream is measured in days, not hours..... it's not corroded at all.... Top marks for the "firebrick" that's close.. ....
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Old 09 August 2005, 08:26   #25
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Originally Posted by Jono
I am taking the p**s somewhat, as it's impossible to tell by picture, descriptions etc, which was rather my point.. but I'll give you some more information and see what you come up with... the weld was 100% radiographed at manufacture.... the equipment runs in the high 700's (centigrade)... The cooling rate when it comes off stream is measured in days, not hours..... it's not corroded at all.... Top marks for the "firebrick" that's close.. ....

?? Part of a nuclear reactor
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Old 09 August 2005, 08:29   #26
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?? Part of a nuclear reactor
Oil refinery... but now I'm making it too easy....
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Old 09 August 2005, 08:32   #27
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Oil refinery... but now I'm making it too easy....

cat cracker
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Old 09 August 2005, 08:33   #28
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And I thought it was part of a ships boiler or something like that lol...

Couldn't tell you then-not there. It does have a layer of corrosion though-that or oxidised nickel.it'd be bright if it was stainless and not corroded.

What DID cause it?!
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Old 09 August 2005, 08:35   #29
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Think I started something here.

Remember the crack isnít in the gearbox itself, itís in the Exhaust chamber between the box and the prop. The bearing itís closest to is the one held in a Ďspider that sits just behind the prop.

Iím struggling to find somebody to weld it at the moment, although I may have located a spare casting, but the guy involved canít check itís the right one until later in the week.

Nasher.
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Old 09 August 2005, 08:37   #30
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Think I started something here.


Nasher.

yeah but it sure beats working !!
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