Steam going straight up chimney

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Keith S
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Steam going straight up chimney

Post by Keith S » Tue Aug 13, 2019 5:45 pm

Hi lads, I've got a problem with a locomotive. I think I know what it is but I'd like to discuss it before taking it apart.

Several years ago I gave my Dad a little live-steam "Porter" locomotive made by Bowande. Just as an aside, this model was I think the first one made by that company and caused a bit of legal trouble because the man who designed it apparently pinched quite a few design features from Accucraft, where he had previously been employed. The loco is no longer available. It is tiny: much smaller than a 16mm scale engine, except maybe a quarry hunslet of the smallest size! It used to run quite well.

Anyway, my Dad moved to Victoria, in Canada, and does not have enough garden space for a garden railway, so the locomotive has been displayed on a shelf for several years. This summer we took it off the shelf for a run. It steamed well but ran quite poorly. It couldn't pull its wagons and while it would run by itself, it was weak. One symptom was that when the regulator was opened, steam went straight up the chimney.

At first I suspected a valve was unseated in one cylinder, because I am used to Roundhouse cylinders. But now I think about it, this engine has piston valves, not "D" valves, so that can't really be the problem.

I now suspect that a piston is allowing steam through, and that this is because somehow an O-ring has become dried-out due to inactivity, or perhaps someone has been pushing the engine back and forth on its display track during the long period it was not steamed (or lubricated!). It looks reasonably easy to remove the cylinder end plates and poke out the pistons. What do you guys suppose the piston ring might be made of? If they aren't a generic size, is there a material that works as a replacement? I am quite certain parts aren't available.

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tom_tom_go
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Re: Steam going straight up chimney

Post by tom_tom_go » Tue Aug 13, 2019 5:47 pm

Are you sure the regulator is opening fully?

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Keith S
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Re: Steam going straight up chimney

Post by Keith S » Tue Aug 13, 2019 5:57 pm

Yes, I'm quite sure it is. I thought the same thing at first, but when it's opened a great deal of steam comes out the chimney, with the locomotive remaining stationary. It will run without a load if helped by a push, but the exhaust beat sounds as though only one cylinder is doing anything. I'm pretty sure it's a cylinder problem.

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Re: Steam going straight up chimney

Post by DonW » Fri Aug 16, 2019 5:28 pm

You might try a plumber's merchant for O rings they use various sizes in taps, shower fittings etc. I had a blister pack of various sizes cannot remember what the smallest size was.

Don

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