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Post by jamienwr on Mar 3, 2008 21:13:54 GMT
Hi all
I am wondering if anyone can help me. I have a little problem with the big end bearings/connecting rods but not sure which is the culprit?
As my pistons seem to be reaching the end of their travel before the wheel has even turned 180 degrees (in either forward or reverse)
I hope someone out there will be able to help me try to solve this little problem
Jamie
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Post by mutley on Mar 3, 2008 21:48:07 GMT
Are you sure your piston rods are the right length? It's usual to machine these to 'fit' the job.This sounds the most likely unless your conecting rods have been made incorrectly.
Andy
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Post by jamienwr on Mar 3, 2008 21:57:25 GMT
Thanks Andy,
I will try and remove the piston & conecting rods to get the full dimenstions as soon as I find a free moment.
Dose anyone know what the the lengths of the coupling/piston rods should be?
Jamie
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Post by baggo on Mar 4, 2008 0:36:01 GMT
Hi Jamie,
which loco are we talking about? (Speedy perhaps?)
If the pistons are fouling both front and rear cylinder covers then there are several possibilities: The cylinders have been machined too short, the spigots on the cylinder covers are too long, or the pistons are too thick. Another possibility is that the throw of the crank pins is more than it should be.
If the pistons foul the front cylinder covers but not the rear ones, the piston rods or connecting rods are too long.
If the pistons foul the rear cylinder covers but not the front ones, the piston rods or the connecting rods are too short.
John
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Post by jamienwr on Mar 4, 2008 5:29:29 GMT
Hi John
I'm talking of the LSBC "pansy" design.
the piston is fouling both the front and back cylinder covers, I will look at all possiblities but I thought I'd seek expert advice before I dived head first incase anyone else has had the same problem (as this is my first project locomotive although I have one running atm aswell).
Jamie
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Post by baggo on Mar 4, 2008 9:58:53 GMT
Hi Jamie,
Apparently there were some errors on the early drawings. Alan's website gives a list of them but there are none relating to the cylinders.
I have the original ME's with the construction series so if you need any dimensions checking just let me know and I'll look them up.
John
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Post by Deleted on Mar 4, 2008 13:53:01 GMT
Hi Jamie
Are you sure it is the pistons hitting the cylinder covers, if the coupling rods are on the loco it could be the quartering. It may be worth taking the coupling rods off to be sure. It is amazing how many locos have tight spots because the quartering is out.
If the pistons are hitting both end covers then the crank stroke is too long for the available space in the cylinder. It doesn't matter whether the error is in the drawings or the manufacture, what is needed is to alter parts to make it work. As John said you can thin down the cylinder cover spigots, or thin down the piston (or both). Before you alter anything just check how much is likely to have to come off. If the problem is fairly small, say skimming a few thou off the piston should fix it, but if the crankaxle stroke has been made 1/4inch too long you'll have to bite the bullet and make a new crank, best to work this out first before ruinining the pistons trying to fix it and then having to make a crankaxle and new pistons.
Hope this helps
Trevor
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