LNER 4771 Green Arrow

speechless as in thats a good idea or what the hell is this guy on about??
thanks
Patrick

 

Speechless, as in "a little knowledge is a dangerous thing" I imagine! Are you familiar with locomotive cylinders?

 

Personally I'm looking forward to seeing a set of V2 cylinders bored out by 6" with a liner of 3" wall thickness fitted. It won't be something you see every day!

 

Imagine the increase in steam required, will have to a good job on that boiler.

Will be like a V2, R8 turbo in comparison to the original item!!!!!!

 

what i have not put in my profile is that i am a model engineer with 2 locomotives under my belt and i have shadowed a gualifed engineer who has built many locos so i know what in talking about, the 6 inch 3 inch diameter thing is quite simple as if you bore the cyclender block out by another 6 inches in diameter or 3 inch in radius then to get the original diameter back a tube with at least a 3 inch thick wall which is then placed in liquid nitrogen which shrinks it and then it is placed into the block and expands effectively locking it into place then the block could be machined for channels to put the steel sections in which are then welded to the new cyclender liners thus taking most of the stress off the casting which then could be metal stitched to get rid of the cracks then one back on the frames the cyclenders could be re board true and to the correct diameter simple
thanks
Patrick

 

I rather think that if you bored the cylinder block out by 6" you would be left with an awful lot of air and very little metal in which to insert any liner. When you bore out cylinders to insert a liner you are talking about fractions of an inch not inches. I also wonder just how much liquid nitrogen would be required to shrink a 3" thick liner to fit in.

 

I can see what your getting at I think patrick, basically your saying fit a set of massively over sized liners to compensate for over boring the cylinders in order to retain the original dimensions?

Chris

 

yes thats the idea so adding a large liner would allow the original bores of the cyclenders and increase the strength of the casting

 

But as hasbeen pointed out, locomotive cylinders do not have massively thick walls, and you can't bore away what isn't there in the first place! You could fit liners with very thick walls, but then the cylinders would be very under size! Finally, and I think this is the crucial point, I don't think the problem lies with the cylinders themselves, the top of the monoblock is corroded away around the exhaust manifold, leaving little to support the blast pipe. If it becomes detatched whilst running a serious blowback can ensue This is not an uncommon problem, even with two cylinder engines (I seem to recall something similar with 75029 a few years ago) but the monoblock would be very much harder to repair.That's how I understand the problem, I'm sure someone like Anthony, who is more conversant with it, will correct me if I'm wrong.

 

"yes thats the idea so adding a large liner would allow the original bores of the cyclenders and increase the strength of the casting"

The idea is simple enough but as my learned friends have said you might get another 1/2 inch out tops to be replaced with an appropraite ie thicke liner and the means of stopping that liner slipping.
Lining up the middle cylinders on gresleys machines is not new and was done on some of his pacifics to compensate for the 'overworking' by the middle cylinders due to the conjugated gear . over all the machine would be slightly less powerfull.

If it was simply a case of doing this im sure it would have been done by now ...

 

Precisely!