what are the consequences of this!!
07-09-2003, 12:29 PM
#31
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Re:what are the consequences of this!!
I'm thinking we can all agree on one thing here, that durned hole is either gonna get bigger or smaller, it ain't gonna stay the same size 
. I also know that my tools also shrink when cold, not that that means anything ;D . Now, lets see who wins cause I know the answer but i'm not going to say.. na na...<br><br>Duane W.
. I also know that my tools also shrink when cold, not that that means anything ;D . Now, lets see who wins cause I know the answer but i'm not going to say.. na na...<br><br>Duane W.
07-09-2003, 12:51 PM
#32
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Re:what are the consequences of this!!
I think we should change the name of this web site to Diesel Engineering, Science,Resource and debate. DESRD.com 
<br><br>just wait till the durn thing falls out, buy a new 3 piece manifold, then you will have the chance to reinstall the probe correctly. OR-- use J.B.Weld ;D
<br><br>just wait till the durn thing falls out, buy a new 3 piece manifold, then you will have the chance to reinstall the probe correctly. OR-- use J.B.Weld ;D
07-10-2003, 07:19 PM
#34
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Re:what are the consequences of this!!
This has all been very interesting to me. I have been in the maintenance industry for the last 30 years and have installed numerous couplings and gears. They were anywhere from the same size to a few thousanths tight. We always heated the coupling or gear and put a little never-sieze on the shaft and everything fit just fine. I have never heard of shrinking the gear and heating the shaft.<br><br>Barry
07-13-2003, 10:25 AM
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Re:what are the consequences of this!!
Today on Two Guys Garage, they were installling a ring & pinion in a rear end. They had an innovative way to heat the bearing that goes on the pinion: They placed it on the griddle of a waffle iron!! Pretty 8) Never would have thought of that. Wonder what my wife would say if I wanted to take the griddle out to the garage and heat stuff with it? ("Buy your own!!" would be the most likely response).
07-13-2003, 11:10 AM
#36
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Re:what are the consequences of this!!
Wonder what my wife would say if I wanted to take the griddle out to the garage and heat stuff with it?
07-13-2003, 12:44 PM
#37
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Re:what are the consequences of this!!
"YES. Like I said before, its like adding water to a sponge. The reason the gear gets bigger is because the metal is expanding. Becoming larger if you must. The reason the hole in the manifold is getting smaller is because the manifold is getting larger forcing the hole to close. Its the same reason that if you have a crack in your exhaust manifold the leak gets less when your motor is hot."
Well, for starters, *I* am not at all sure such a crack DOES "get less" when heated, I sure haven't seen that tendency demonstrated...
;D
I wuz gonna stay out of this after my last post, but since it still continues, will offer one more point - and it helps if you followed the pointer supplied further back on principles of expansion.
IN that example, a square piece of metal was shown with a hole in the center - it also showed and gave equations as to the GROWTH factor of BOTH the center hole AND the outer dimensions of the metal - are we together here?
NOW, if we agree that as shown in that display, BOTH the dimensions of the WHOLE piece, AND the center hole DO increase with heat while in the FLAT plane, WHAT happens if that exact SAME piece of steel is rolled into a CYLINDER?
SAME exact piece of steel, same overall dimensions, same center hole, only NOW bent into a cylindrical shape rather than FLAT! Surely we will agree that when heat is applied, there will be the same increase percentage in the LENGTH and circumference of that cylinder material as though it was still flat - but would we NOW claim that while every OTHER dimension increases exactly as before, the HOLE alone now gets SMALLER rather than LARGER as it did before, while it was still in a flat state? WHY would there be ANY expansion difference caused by its being in a flat, as opposed to a cylindrical shape?
And what equation would you point to to back that claim up? Doesn't really make much sense, now does it!
And in reality, ALL a manifold is, is a collection of one or more "tubes" or "cylinders" that carry exhaust gasses away from the engine - so what makes the difference between that and the cylinder described above? Why would anyone think it would behave any differently?
Well, for starters, *I* am not at all sure such a crack DOES "get less" when heated, I sure haven't seen that tendency demonstrated...
;DI wuz gonna stay out of this after my last post, but since it still continues, will offer one more point - and it helps if you followed the pointer supplied further back on principles of expansion.
IN that example, a square piece of metal was shown with a hole in the center - it also showed and gave equations as to the GROWTH factor of BOTH the center hole AND the outer dimensions of the metal - are we together here?
NOW, if we agree that as shown in that display, BOTH the dimensions of the WHOLE piece, AND the center hole DO increase with heat while in the FLAT plane, WHAT happens if that exact SAME piece of steel is rolled into a CYLINDER?
SAME exact piece of steel, same overall dimensions, same center hole, only NOW bent into a cylindrical shape rather than FLAT! Surely we will agree that when heat is applied, there will be the same increase percentage in the LENGTH and circumference of that cylinder material as though it was still flat - but would we NOW claim that while every OTHER dimension increases exactly as before, the HOLE alone now gets SMALLER rather than LARGER as it did before, while it was still in a flat state? WHY would there be ANY expansion difference caused by its being in a flat, as opposed to a cylindrical shape?
And what equation would you point to to back that claim up? Doesn't really make much sense, now does it!
And in reality, ALL a manifold is, is a collection of one or more "tubes" or "cylinders" that carry exhaust gasses away from the engine - so what makes the difference between that and the cylinder described above? Why would anyone think it would behave any differently?
07-13-2003, 03:47 PM
#38
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Re:what are the consequences of this!!
Well I have never seen somebody successfully heating the shaft and cooling the gear to put that stuff together. But what do I know ???<br>Over here in the more primitive regions we usually heat the gear and cool the shaft. <br>I think that putting the probe in without a compression fitting is rather bad even if you press or shrink it in because a: the probe will be crimped by the short portion it is compressed and b: because there's no fitting the probe will work loose due to the differences in expansion factors not taken up by the elasticity of the compression fitting. <br>Just my 2c <br><br>AlpineRAM
07-13-2003, 04:13 PM
#39
It's my pot and I'll stir it if I want to. If you're not careful, I'll stir your's as well!
Re:what are the consequences of this!!
Gary is on the right track. It seems to me that in this argument, sorry, discussion, that there is a little mixing of oranges and apples. Expansion and contration DO work differently when applied to a flat surface (orange) as opposed to a cylindrical surface.(apple)<br>For things like bearings on shafts or ring gears on flywheels the part that goes OVER is always heated (expanded) and the part the goes INSIDE (ie a shaft) is always cooled (contracted)<br>Now, as Gary stated, when you have a cylindrical object and bore a hole in it, then the physics behave a little differently. Sure, the cylinder grows larger in diameter when heated, and longer in length, but a hole somewhere in the middle gets smaller in diameter.<br>Hope this helps to clarify things a little.
07-13-2003, 04:41 PM
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Re:what are the consequences of this!!
"For things like bearings on shafts or ring gears on flywheels the part that goes OVER is always heated (expanded) and the part the goes INSIDE (ie a shaft) is always cooled (contracted)"<br><br>Mextan<br><br>That sums it up perfectly. Heat the hole and cool what is going in it. When shrink fitting aircraft components we put the object with the hole in the oven and the piece going in it in dry ice or liquid nitrogen.<br>
07-13-2003, 04:42 PM
#41
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Re:what are the consequences of this!!
Mexstan: As I read Gary he points out that the behaviour will be the same whether rolled up to a cylinder or not. <br>I do not think that physics will work differently. <br>Some factors that can change the actual behaviour from out theoretical musings are that we talk about a cylinder that is not connected to anything that may have different thermal behaviour and we assume a homogenous heating of the object. <br>What we'll see in reality is that the exhaust manifold is bolted to the cyl. head on the one side and to the turbo on the other side and is nowhere near the same temperature throughout the casting.<br><br>AlpineRAM
07-13-2003, 05:51 PM
#42
It's my pot and I'll stir it if I want to. If you're not careful, I'll stir your's as well!
Re:what are the consequences of this!!
AlpineRAM, now we are really getting technical, but you are right. In something like an exhaust manifold the temps are all over the place. Something I neglected to mention was that the mass of an object can change to some extent what happens to a hole near the middle. But now we are getting way too theoretical and who cares anyway. (except you picky engineering types reading this)
07-13-2003, 06:25 PM
#44
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Re:what are the consequences of this!!
"Mexstan: As I read Gary he points out that the behaviour will be the same whether rolled up to a cylinder or not.
I do not think that physics will work differently."
EXACTLY my point!
Why on earth would the "physics" change simply because you took the exact SAME piece of metal, and rolled it into a cylinder instead of leaving it FLAT? Don't make no sense at all!
Why is this important? well, maybe NO reason to many or most of us - but proper understanding of the properties of heat and cold, and their effect upon metals is BASIC to design and operation of mechanical devices exposed to those extremes - as demonstrated by the question that started all this! How could engineers design engines and transmissions WITHOUT taking into account the effects of changing temperatures on what they design?
And that goes for ALL the varying shapes and sizes of components in our vehicles, not just the flat surfaces... ;D ;D
I do not think that physics will work differently."
EXACTLY my point!
Why on earth would the "physics" change simply because you took the exact SAME piece of metal, and rolled it into a cylinder instead of leaving it FLAT? Don't make no sense at all!
Why is this important? well, maybe NO reason to many or most of us - but proper understanding of the properties of heat and cold, and their effect upon metals is BASIC to design and operation of mechanical devices exposed to those extremes - as demonstrated by the question that started all this! How could engineers design engines and transmissions WITHOUT taking into account the effects of changing temperatures on what they design?
And that goes for ALL the varying shapes and sizes of components in our vehicles, not just the flat surfaces...
;D ;D
07-14-2003, 01:36 AM
#45
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Re:what are the consequences of this!!
OK PLEASE READ THIS CAREFULLY!!! I never said to heat the shaft and cool the gear. If you think I did then show me a quote. Read all the responses before you add your opinion or info. <br>Now to whomever who thinks they cant get their point across without being rude... All I'm saying is I understand the principals of expansion. If you havent seen a crack in a manifold shrink when the engine is hot well then I can see where you would disagree with me. I dont really understand why this happens except for the fact that maybe the manifold is bound to the motor which doesnt allow the same means of expansion that a non-bound piece of metal would normaly see? Maybe the fact that the manifold is hollow means it doesnt expand like something without voids in it? If everything just got simply bigger when hot then how simple engine building would be. Why worry about tolerances anymore? Please no one quote me on that.
<br>Now to whomever who thinks they cant get their point across without being rude... All I'm saying is I understand the principals of expansion. If you havent seen a crack in a manifold shrink when the engine is hot well then I can see where you would disagree with me. I dont really understand why this happens except for the fact that maybe the manifold is bound to the motor which doesnt allow the same means of expansion that a non-bound piece of metal would normaly see? Maybe the fact that the manifold is hollow means it doesnt expand like something without voids in it? If everything just got simply bigger when hot then how simple engine building would be. Why worry about tolerances anymore? Please no one quote me on that.