Paddlewheeler trunk steam engine - help me id it

[kno3]

Hi all,

This is my first posting here, although I've been reading the forum for a while, with great interest. Now I need some help:

I have an engine here for identification. Bought it recently (without any history) and according to my Internet research it is called a "trunk steam engine". As you can notice, it is not the usual configuration. It is a double acting engine with slide valves, but, rather than having piston rods, it has a more peculiar arrangement: the piston rods are actually wide tubes and the con rods run into these tubes. The result is a very compact engine (the same size as an equivalent oscillator) but it is still having reasonably long con rods.
The following parts (at least) are made from bronze castings: cylinders, valve chests, base, crankshaft frame, eccentrics, eccentric straps.

Here are the pictures:

2010-11-07 007 by -kno3-2, on Flickr


2010-11-07 001 by -kno3-2, on Flickr

Does anyone know who made the castings, or perhaps the engine?

 

[kno3]

Hello Pat,

Thanks for the animation and info. I really hope to find out more about this engine. Meanwhile I am having a missing part made, so I'll hopefully be able to test run it soon. The plan is to build a paddlewheeler later on and to use this engine in it.
Still have to determine what the actual volume of the cylinders is, to be able to find a suitable boiler. The volume, because of the trunks, is certainly much less than the really large cylinders would make it appear.

Thanks for the kind words regarding my tug. If you want more pictures of it I can post a link.By the way, I'd like to see more of that engine you have in your profile pic, it is really nice.

 

[kno3]

Hello again,

I have started disassembling the engine for clean-up and also because I was very curious about the pistons. As you can see, it didn't have any gaskets and also no traces of liquid sealant. I guess whoever cleaned this engine up in the past and painted it, didn't run it, just kept it for display. YOU CAN CLICK ON THE PICTURES FOR A LARGER VIEW.

2010-11-27 003 by -kno3-2, on Flickr

Here is what I have found inside, the piston is as i had expected, wider than the trunk.

2010-11-27 004 by -kno3-2, on Flickr

And a close-up of the piston + trunk assembly.

2010-11-27 005a by -kno3-2, on Flickr

Well, given this piston configuration, it means that one side of the cylinder (upper) has much less volume than the other (bottom).
I'm wondering if or how this would affect the way the engine runs. However, since the larger cylinder volume is on the upper stroke, perhaps things get somehow balanced, because it requires more power to lift such a heavy cylinder + trunk assembly than to lower it. Seems reasonable - does it make sense to any of you?

Here are some more views of both pistons out of the cylinders.

2010-11-27 014 by -kno3-2, on Flickr


2010-11-27 017 by -kno3-2, on Flickr

The upper cylinder covers have yarn for insulating the trunk.

2010-11-27 018 by -kno3-2, on Flickr

Well, I am still considering how to proceed with getting this engine back to running condition. The option I'm thinking about are:
1. Re-assemble using liquid gasket (Hylomar), which seems the easiest solution.
2. Make some Teflon gaskets for the cylinder covers (and bottom covers as well?), as I have some Teflon sheet.
3. Since the pistons are plain, I am also considering cutting a small groove into them, to hold either an O-ring or some rolled Teflon tape. This should greatly improve the running of the engine, especially at low pressure.

What do you think?

 

[bearcar1]

KN, that is a beautiful specimen of an engine. I cannot help you in identifying it's origins but I can extend my opinions regarding your other questions. Now bear in mind that I am a bit 'old fashioned' (just old ?!?) ;D and personally do not appreciate seeing products such as Hylomar used on model engines, it gives me the impression that not enough attention was given to the fittment of the mating surfaces or that the builder is/was just too lazy to make up fitted gaskets or just did not care. Use the Teflon sheeting as you described or cut the gaskets out from some heavy Kraft paper (the brown stuff that is used for grocery bags) and lightly treat them with oil. I feel the same about the use of Teflon tape as a piston ring, although that method seems to be getting more widely accepted over the use of graphited yarn. The latter does create more mess when steam is used but I feel the extra overall lubrication is worth it. Of course opinions and techniques will vary widely as with many operations in this hobby, but in the end, I think that you will be much happier with making up gaskets over any of the paste sealers. Again, this is just my $.02 and nothing more. I am envious of your newly acquired gem and can not wait to see it restored and hopefully running again.

BC1
Jim

Jim B.

 

[kno3]

Thank you for the advice. I'll try to cut some gaskets then. Still have to decide if paper or Teflon. Someone told me that Teflon gaskets creep under pressure? Did anybody experience that?

I have managed to disassemble the piston+trunk and this is what it looked like. Lot's of dirt accumulated in there. The connecting rod is not bent, just thinned on one side to clear the trunk.

2010-11-27 023 by -kno3-2, on Flickr

After some cleaning up:

2010-11-27 024 by -kno3-2, on Flickr

During disassembly, a steel screw decided to shear off...

2010-11-27 025 by -kno3-2, on Flickr

I have spent an hour filing the stub flat, and then carefully boring it out with 1 and 1,5 mm drills. Then I was able to remove it and luckily I didn't damage the thread in the brass part!

2010-11-27 026 by -kno3-2, on Flickr

 

[kno3]

Yes you guessed right! ;D

Actually there is enough material to cut a groove into, below that lip there is a considerable ring of brass. I know that engines can run well without o-rings, but there is always blow-by. That means lost steam, less performance, and often a reduced ability to run slowly. I have added O-rings to other engines (to an older Cheddar Puffin to a Pipit, also to an ancient Stuart twin wobbler) and in all cases the performance was better: they would start turning at lower pressure etc.

Regarding the gaskets, I have decided to make some paper ones. I am going to use Teflon tape for the valve rod packing.

I guess it must be a very rare model, because I have posted it on several forums and nobody could offer a clue about the maker. There was a single person who thought it could be from Stevens Model Dockyard, but it doesn't appear in the catalogues.

Another thing: what could the red stuff inside the piston be? It was in several places in the cylinders (valve chests etc.) and I had to work a lot to remove it. It was quite hard and turned to dust when scraped. Some sort of ancient sealing compound?