Paddleducks
Other Marine Models => Live steam => Topic started by: kno3 on November 08, 2010, 08:55:53 AM
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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:
(http://farm2.static.flickr.com/1105/5155196471_d056d6cfbd.jpg) (http://www.flickr.com/photos/47590525@N04/5155196471/)
2010-11-07 007 (http://www.flickr.com/photos/47590525@N04/5155196471/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
(http://farm5.static.flickr.com/4048/5155839366_8a5706f680.jpg) (http://www.flickr.com/photos/47590525@N04/5155839366/)
2010-11-07 001 - Copy (http://www.flickr.com/photos/47590525@N04/5155839366/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), 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!
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I'm sure I've seen this engine before, and I've been wracking my brains trying to think where!
I've searched and searched without luck, but I believe it was the engine used in a model paddle tug called Pilat. I have no idea who designed it, but try searching for the tug and you might just hit on the engine....
The plans for Pilat were available from Model Boats magazine, but I'm not sure if the engine plans were available from the same source?
Regards
Eddy
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Thank you for the information. I have only found this reference to a tugboat named Pilat: http://www.taubmansonline.com/MRBPILAT.htm
Unfortunately they don't show any pictures. I have e-mailed them, let's hope I can find out more.
Do you remember if you saw this or a similar engine in a publication or for real?
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Attached is an image of the model of Pilat that I had a few years ago.... Electric powered. But this was the same as the model I saw the steam engine in.
I vaguely remember chatting to the owner of the steam powered one, and I'm certain that he said the engine was made from commercially available plans, and was designed specifically for Pilat.
Regards
Eddy
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http://www.dreamstime.com/stock-images-old-red-tugboat-image5736464 ...has the same name kno3.......sorry but it is not a paddler.......Derek
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Then we had another PILAT here on PD's......
quote author=Hankwilliams link=topic=4766.msg22924#msg22924 date=1251279766]
Your boat now has the status of a live steam antique and technical model-monument, you should protect it in a good way to the future.
And why not make a steam up with pictures, the machinery seems functionable?
My first boat I`ve built 1966 in the age of 13, it was a tug named "Hamburg II" by Robbe.
However I was very interested in this years to make a live steam model, this was prevented throught the lack of experience, available steam engines and parts and least not last of money.
In 1968 I made my first plan built 1 : 50 scaled sternwheeler "Marieville", driven by electric.
Later there was a long break of model making until 1989, when I make the first live steam boat, the well known "Pilat", driven by an oscillator, which I mentioned a few days ago.
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Attached is an image of the model of Pilat that I had a few years ago....
is that the one that was at 'paddler day 2008?'
http://www.paddleducks.co.uk/smf/index.php?action=gallery;sa=view;id=2605
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Yes that's the one Mick - It's still in our club, so it still puts in an appearance... I should just clarify, that it's the model I used to own, which is electrically powered, NOT the steam one!
Regards
Eddy
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Hi Eddy,
I`ve build my "Pilat" in 1989 and she is steam driven by a turned V-oscillator engine, bore 10 mm, stroke 20 mm. I turned the engine, so the shaft is above the engine frame, the position is approximately near the shaft of the paddlewheels.
With a gear reduction of 1 : 3,5 power and speed are sufficiend.
Sorry, I`ve no photo in the moment. I had extendet the lenght of the boat from 140 to 150 cm. For my opinion, this gives a better proportion of the ship - the original "Pilat" lenght was about 65 m.
In 1 : 33 this would be a model of nearly 2 meters lenght - some difficultis about transport are to expect.
Tom
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In the plans of "Pilat" also an oscillating engine, but direct driven with no gear reduction, is to see. It`s not a trunk engine and I don`t think, that the engine on the pics was used in "Pilat", because the paddlewheels seems too narrow.
But why not use for this model? It would be not very difficult, to alter the wheels to wider dimensions.
Tom
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Thanks for the answers everyone. It looks like it is not the engine for the Pilat tugboat then?
Since it's made of castings, I thought someone might recognize them, but no luck so far on several forums.
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Ant luck getting the missing part made?, if not I could probably help just send me a PM..
Stew
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Thanks, I already have a kind person doing it for me.
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I think a Trunk engine is also know as an oscillating engine. The only trunk engine I have ever seen is the non-steam replica on HMS Warrior at Portsmouth, which looks like an oscilating engine, like those on most of the Dresden paddle steamers, Gisela and Hjejlen, lying on its side to power the screw
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No, in a trunk engine the cylinders are fixed. Oscillating engines are different beasts.
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To clarify a little, (or confuse a lot?), here's a typical trunk engine...
The trunk engine, a type of direct-acting engine, was developed largely as a result of the demand for warships to have a powerplant with a profile low enough to fit entirely below a ship's waterline, where it would be as safe as possible from enemy fire. The type was generally produced for military service by John Penn.
This type of engine had a horizontal cylinder, through the centre of which passed a cylindrical "trunk" or passage containing the connecting rod. The walls of the trunk were either bolted to or cast as one piece with the piston, and moved back and forth with it. The working portion of the cylinder was annular or ring-shaped, with the trunk passing through the centre of the cylinder itself.
Eddy
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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.
(http://farm5.static.flickr.com/4132/5211575050_201b247518_m.jpg) (http://www.flickr.com/photos/47590525@N04/5211575050/)
2010-11-27 003 (http://www.flickr.com/photos/47590525@N04/5211575050/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
Here is what I have found inside, the piston is as i had expected, wider than the trunk.
(http://farm5.static.flickr.com/4103/5211575202_938d651deb_m.jpg) (http://www.flickr.com/photos/47590525@N04/5211575202/)
2010-11-27 004 (http://www.flickr.com/photos/47590525@N04/5211575202/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
And a close-up of the piston + trunk assembly.
(http://farm6.static.flickr.com/5206/5210973981_5f407e4427_m.jpg) (http://www.flickr.com/photos/47590525@N04/5210973981/)
2010-11-27 005a (http://www.flickr.com/photos/47590525@N04/5210973981/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), 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.
(http://farm5.static.flickr.com/4091/5210974117_f763c85011_m.jpg) (http://www.flickr.com/photos/47590525@N04/5210974117/)
2010-11-27 014 (http://www.flickr.com/photos/47590525@N04/5210974117/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
(http://farm5.static.flickr.com/4084/5210974271_245e107d17_m.jpg) (http://www.flickr.com/photos/47590525@N04/5210974271/)
2010-11-27 017 (http://www.flickr.com/photos/47590525@N04/5210974271/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
The upper cylinder covers have yarn for insulating the trunk.
(http://farm6.static.flickr.com/5042/5211575674_df4912bbb4_m.jpg) (http://www.flickr.com/photos/47590525@N04/5211575674/)
2010-11-27 018 (http://www.flickr.com/photos/47590525@N04/5211575674/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), 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?
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Hi PD's....& :gift .....what a great project kno3 & :kewlpics
1) lets call the extension side of the piston the BLIND side & the retraction side of the piston the ROD side
2) it would be interesting to understand the ratio of diameters ie., the blind side diameter & the rod diameter
3) we must remember that all simple double acting steam engines have this 'blind side to rod side ratio'
4) In photograph 2010.11.27.017...in the left hand cylinder base we see counterbores @ 10.0, 7.0 & 3.0 o-clock
5) we also see three equally spaced similar diameter pegs on the piston blind face
6) I assume these are to limit the piston stroke & hence not block the steam admission ports & get a full face for liftoff ?...however the crankshaft 'throw' limits piston stroke & so shouldn't bottom out anyway..... :shoot
7) In photograph 2010.11.27.004 & 005a..... :hammer ...is the rod side gland upside down :shhh
8) the rod side gland has very little parent material on the ID of the PCD of the bolt holes to 90 degree face for Hylomar to seal ...teflon sheet would have the same issue & be difficiult to cut :crash with such a thin surface between diameters
9) you could use the same setup in the lathe when you make the rod side gland o-ring cavities...& also machine o-ring cavities for the spigot diameters ....that would solve those two issues :whistle
10) this then leaves the piston sealing........this page is near full limit......... :ranting ...I will post another page .....Derek
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Hi PD's....& :gift .....what a great project kno3 & :kewlpics
1) lets call the extension side of the piston the BLIND side & the retraction side of the piston the ROD side
2) it would be interesting to understand the ratio of diameters ie., the blind side diameter & the rod diameter
3) we must remember that all simple double acting steam engines have this 'blind side to rod side ratio'
I didn't get to measure things up yet, but it is on my to do list.
4) In photograph 2010.11.27.017...in the left hand cylinder base we see counterbores @ 10.0, 7.0 & 3.0 o-clock
5) we also see three equally spaced similar diameter pegs on the piston blind face
6) I assume these are to limit the piston stroke & hence not block the steam admission ports & get a full face for liftoff ?...however the crankshaft 'throw' limits piston stroke & so shouldn't bottom out anyway..... :shoot
No they are not there to limit anything. They are 3 screws that hold the piston together, and the 3 counter-bores are there so that these screws don't hit the cylinder bottom. I'll post some more pictures with the piston disassembled.
7) In photograph 2010.11.27.004 & 005a..... :hammer ...is the rod side gland upside down :shhh
8) the rod side gland has very little parent material on the ID of the PCD of the bolt holes to 90 degree face for Hylomar to seal ...teflon sheet would have the same issue & be difficiult to cut :crash with such a thin surface between diameters
9) you could use the same setup in the lathe when you make the rod side gland o-ring cavities...& also machine o-ring cavities for the spigot diameters ....that would solve those two issues :whistle
You've lost me with all the abbreviations. But if you look at this pic closer
(http://farm6.static.flickr.com/5042/5211575674_df4912bbb4.jpg) (http://www.flickr.com/photos/47590525@N04/5211575674/)
2010-11-27 018 (http://www.flickr.com/photos/47590525@N04/5211575674/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
you'll see how the trunk (rod, whatever) is sealed: the smaller ring compresses a spiral of (cotton?) thread, which you can see in there. That thread is kind of short on one cylinder, so I'll replace both with Teflon tape which I will twirl first, to make a thread out of it. Done this before, it is quite easy and very effective.
10) this then leaves the piston sealing........this page is near full limit......... :ranting ...I will post another page .....Derek
Shoot! ;D
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Now back to business: 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.
(http://farm6.static.flickr.com/5086/5212751898_31934244ac_m.jpg) (http://www.flickr.com/photos/47590525@N04/5212751898/)
2010-11-27 023 (http://www.flickr.com/photos/47590525@N04/5212751898/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
After some cleaning up:
(http://farm6.static.flickr.com/5088/5212153951_92c44929c8_m.jpg) (http://www.flickr.com/photos/47590525@N04/5212153951/)
2010-11-27 024 (http://www.flickr.com/photos/47590525@N04/5212153951/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
During disassembly, a steel screw decided to shear off...
(http://farm5.static.flickr.com/4085/5212154099_af822a8447_m.jpg) (http://www.flickr.com/photos/47590525@N04/5212154099/)
2010-11-27 025 (http://www.flickr.com/photos/47590525@N04/5212154099/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), 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!
(http://farm5.static.flickr.com/4128/5212154315_1046afa73f_m.jpg) (http://www.flickr.com/photos/47590525@N04/5212154315/)
2010-11-27 026 (http://www.flickr.com/photos/47590525@N04/5212154315/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
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mmmmmmmmmmm :whistle
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 :hammer :hammer ....Derek
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Just to clarify, the abreviations Derek has used:
ID = Inner diameter (or Inside Diameter)
PCD = Pitch Circle Diameter
Regards
Eddy
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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 :shoot ....PCD was a silly term to use .....Derek
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OK now I think I know where the misunderstanding is: I won't put any Hylomar there. The Hylomar was meant for sealing the larger ring to the cylinder (but I'll try to make a gasket first).
To make things clear - the ring with 4 screw holes compresses the gland packing and fits into the ring with 6 holes (which is the cylinder cover):
(http://farm5.static.flickr.com/4084/5210974271_245e107d17.jpg) (http://www.flickr.com/photos/47590525@N04/5210974271/)
2010-11-27 017 (http://www.flickr.com/photos/47590525@N04/5210974271/) by -kno3-2 (http://www.flickr.com/people/47590525@N04/), on Flickr
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Hi PD's....just thinking again kno3 :sorry
14) the cylinder barrels are probably bolted in the same manner to the lower engine plate....so will require re-gasketing
15) the steam chests will also have inner & outer faces that will also require gasketing
16) JMC uses 0.02 mm thick TEFLON sheet for his engine gaskets...although I suspect he has purpose built dies to stamp out his gaskets
17) TEFLON sheet material is rather unforgiving & if used would require far higher bolt torque levels to achieve steam tightness...over the Hylomar steam sealant
17) one of the better methods of cleaning up horizontal engine component surfaces is a 12"square pane of glass + a sheet of 1200 W&D paper...then hand rotation lap or <<<< ....>>> lap with water...you will see evidence of bronze/brass dust in the water ...but essentially the amount of material removal is near non measurable for our purposes
18) you also mentioned in your very first post here that you thought the steam valve gear rod thread was imperial.....is this the case? & are all the engine dimensions imperial?
Keep us posted........Derek :coffee.......
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Hi PD's....just thinking again kno3 :sorry
14) the cylinder barrels are probably bolted in the same manner to the lower engine plate....so will require re-gasketing
15) the steam chests will also have inner & outer faces that will also require gasketing
You are right about both.But the steam chests only require 1 gasket as they have no separate cover.
18) you also mentioned in your very first post here that you thought the steam valve gear rod thread was imperial.....is this the case? & are all the engine dimensions imperial?
Keep us posted........Derek :coffee.......
Yes, the screws and threads are BA sizes.
Thanks for the advice re. Teflon and lapping.