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[kno3]

Hi all,

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 so it doesn't wear off prematurely.

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 - Copy by -kno3-2, on Flickr

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

2. As you can see in the picture with the yellow arrows, it is missing the valve rod crosshead on one side. This is a brass fork, I assume it has some sort of imperial thread.

Is anyone here with machining capabilities and suitable imperial thread cutters able to make me a new part (perhaps using the other one as a template)?
Please let me know here or via PM.

Thanks!

[kno3]

Hello,

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?

[kno3]

Since nobody seems to think anything regarding my engine  , I'll go ahead with taking it apart.

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

[derekwarner]

we @ Paddleducks think something about this new/old engine stripdown........very interesting....Derek  _____________________________________________________________________________________________________________________

Thanks Eddy......please see that attachment as ......

the rod side gland has very little parent material on the ID of the bolt holes to 90 degree face for the Hylomar to seal ...teflon sheet would have the same issue & be difficiult to cut  with such a thin surface between diameters

Sorry all  ....PCD was a silly term to use .....Derek

 kno3 gland surface.JPG (78.45 kB, 640x480 - viewed 1 times.)
« Last Edit: Today at 01:37:37 PM by derekwarner_decoy » Report to moderator    121.218.203.118 derekwarner_decoy ...Wollongong Australia.Eddy Matthews
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View ProfileWWWPersonal Message (Offline)Re: Paddlewheeler trunk steam engine - help me id and restore it
« Reply #22 on: Today at 12:17:54 PM »Reply
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Just to clarify, the abreviations Derek has used:

ID = Inner diameter (or Inside Diameter)
PCD = Pitch Circle Diameter

Regards
EddyReport to moderator    Logged .derekwarner_decoy
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View ProfileEmailPersonal Message (Online)Re: Paddlewheeler trunk steam engine - help me id and restore it
« Reply #21 on: Today at 12:11:40 PM »ReplyModifyRemove
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mmmmmmmmmmm 

11) you certainly have sufficient room for piston o-rings & gland spigot o-rings
12) we have previously discussed the advantages & disadvantage of both VITON & Silicone o-rings as they both have a very low abrasion resistance...but are suitable for our ~~~~~150 degrees C steam temperature when coupled with steam oil, however we must also remember that o-ring manufacturers nominate 1.6 umRa as the required surface roughness
13) we also must remember that TEFLON has ZERO memory & will not pressure energise in our low pressure dynamic applications ....this is totally different to high pressure static steam gland spindle application where if we get a bypass, the gland is mechanically tightened to compress the TEFLON packing

It will also be interesting to learn the diametrical clearances between the piston & the barrel ....& also the rod & the gland.......as Viton & Silicone also must have minimal exrusion gaps    ....Derek

[ooyah/2]

Hi Knor3

I have just picked up your post on the paddle engine.
Regarding "O" rings in the piston you don't say what the piston dia is, a word of caution, do not under any circumstances use   Black Viton or Nitrile rings in the pistons,
They melt and stick to the cylinder wall which requires a rebore and new pistons after you have managed to extract the piston from the cylinder..
Use only Silicone "O" rings.
As you don't say what bore the engine is here are the dimensions for pistons between 9/16" dia and 15/16" dia  The cross section of the ring is 0.103" which requires grooves of 0.087" min to 0.090" max depth and  0.125" wide min to 0.133" max width.
My advice would be to leave well alone. Why.
1-- You will have to grip the trunk in the 3- jaw chuck and I don't think that the wall is thick enough and you may damage it.
2-- To machine the groove you require a flat tip tool, like a parting off tool. it could dig in  with disastrous results and I don't think that you have enough material
on the piston so you may pass through into the space for the small end bearing flange

Looking at the pics of your engine it appears to have been well machined so I would advise to leave it alone.

For the packing in the bottom cover coat it with steam oil and let it soak in or if you can get graphite packing the same section re pack it.
For cylinder head gaskets use brown paper soaked in oil, paper to be about  0.002" thk--- 0.003" thk

Here is a pic of the piston in a just completed Stuart steam pump with the Silicone ring fitted.
George.
klick on for bigger pics.

[Circlip]

Funny how the "Old School" materials are passed over George, not ALL the new stuff is better.

 One thing you  could ask kno3, whoever makes the new link, let them have the pistons and ask them to turn a couple of shallow vee grooves for oil retention in the O/D. Only need to be about 5 - 10Thou (0.1 to 0.3mm) deep. - It acts like a flexible piston ring.

  Regards  Ian.

[ooyah/2]

Hi Ian,
Absolutely true, the youngsters have all forgotten about thick brown wrapping paper and graphite packing, materials that cost so little and easily available.
Some of them have never filed the graphite from a pencil and soaked a bit of cotton string in oil and then rubbed the graphite into the string,
messy but effective.
Old we may be but we have a wealth of knowledge and when you don't have all the new materials to hand you improvise.
George.

[Circlip]

Aye, WE 'ad it tough, seven of us lived in a shoe box

 No, seriously George, our ministerings will either be remembered, cos the search button seems seriously under used. Not going down the Luddite trail, BUT, Tissue paper and Dope is STILL king for sealing Balsa hulls and "Caskermite" likewise for gluing wood tergether.

  Regards  Ian.

[kno3]

Thanks for the advice. I'll think about the piston groove. I have had a closer look at it and there is a pretty thick brass wall there which should be able to take a deep enough groove for some packing material. Shallow oil grooves are another option, but in my experience they bring much less than an o-ring or packing the piston.

Regarding o-rings: I have a few Cheddar engines and all have black rubber (Nitrile?) orings in them, they have work very well so far and are in good shape. I have recently bought some silicone (white) o-rings and they seem somewhat softer. Do they hold up well as piston rings?

Regarding graphite yarn: I wouldn't know where to buy that, although I have graphite and some cotton yarn, so I guess I could make it myself. But twirled Teflon tape worked so well on several engines I have tried, being also clean and neat, that I don't really see why I should resort to graphite yarn.
Is there any advantage performance-wise?

[gondolier88]

Regarding graphite yarn: I wouldn't know where to buy that, although I have graphite and some cotton yarn, so I guess I could make it myself. But twirled Teflon tape worked so well on several engines I have tried, being also clean and neat, that I don't really see why I should resort to graphite yarn.
Is there any advantage performance-wise?

I've used both on model engines and I can't say I've seen an advantage of one over the other- though PTFE tapewas a damn sight cleaner!

A woed of caution though- if a direct flame comes into contact with PTFE it produces Flourine gas, and can make a liquid deposit that eats skin- so if the gland is likely to be near the burner or COULD come into contact with a flame then use graphite.

There is nothing suggesting you couldn't do both if you wanted belts and braces- mix up a thick paste of Graphite and oil and dip your twited PTFE yarn into it before putting it into service.

Greg

[ooyah/2]

kno3.
The black rings in your Cheddar engine are "Silicone "  they also come in red and white they are soft and if the rings in your other engines are hard they are not Silicone.
The groove dimensions allow the soft Silicone to expand 100 times which fills the groove for a gas seal under the heat of the steam and return to their original size when cool.
Can't comment on twisted Teflon as I have never used it.
George.

[derekwarner]

kno3………VITON elastomer o-rings are usually reddish BROWN, however this same elastomer is also produced in GREEN and BLACK with a RED spot

The density of Nitrile = 1.31 g/cm3….the density of VITON = 2.3 g/cm3…we use this little device to batch check VITON o-rings as used in hydraulic cylinders for the steel industry ....Derek


http://www.google.com.au/url?sa=t&source=web&cd=2&ved=0CB4QFjAB&url=http%3A%2F%2Fwww.qualityseals.com%2Forid.html&ei=YuPyTMOVGIa0vgPA17CLDg&usg=AFQjCNFk4-5wcVK0pIZAjMYwKU8O27hrUg

[Circlip]

Good to see that someone has re-invented the "Shore" Schlerascope or bounce-ometer. 

  Regards  Ian.