Mystery steam engine

[chris123]

Looking at the photo - post #65 - it appears that the crank pins are in-line, so the pistons move together. The valves must therefore be configured so the when the bottom of the HP cylinder is open and exhausting, the LP cylinder must have the top cylinder port opened as the intake to receive the HP exhaust. And vice-versa.
Thus there is no way the pistons can move when at TDC or BDC unless carried-over by inertia from a flywheel.
I suggest the flanges on the ends of the crankshaft will have a flywheel on one end, and a coupling to the propeller shaft on the other end. The flywheel is likely to be a solid cylinder, with the diameter about the same as 2 x the radius to the outer end on the big-end side bars, and the length of the flywheel equal to the diameter. That's what I have used on Marine single engines. And although a Compound Twin, this engine acts dynamically as a single cylinder engine.
K2

 

[chris123]

Hi steamchick
The pistons move not in the same motion
I just got a pic for you

 

[chris123]

The condenser just condenses the exhaust steam.
The old engines from the 1840's, such as ship engines, used the vacuum created in the condenser to improve efficiency (perhaps all condensers improve efficiency).
You can reclaim the condensate (water) from the condenser and reuse it in the boiler, assuming you can get rid of the oil.
Oil in a boiler can make it foam, which is not a good thing.
In industrial areas with little access to large amounts of boiler feed water, condensers were a must.
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Yes that realy make sense
And the eccentric would have driven
Such a pump
Isnt it?
Chris

 

[chris123]

I have seen some modern steam engines cast with very complex cores; the german guy, I forget his name, made his own design and had a foundry cast it in gray iron. It took two attempts by a professional foundry to get a complete fill.

Making the cores for one piston valve and one D-valve would not really be any different if they were located between the cylinders, or at the outsides of the cylinders. It would probably be easier to support the cores if they were located on the ends of the cylinders.

As far as machining, using a D-valve between the cylinders could make for some tricky machining, since you would have to reach in.
Like a 20hp Stanley steam auto engine, with two D-valves between the cylinders; you have to reach in to machine the valve faces.

Long castings can be tricky to fill, and you have to make sure one end does not solidify first and draw molten metal from the other end.

It is an impressive cylinder casting, in my opinion, and impressive machining too.
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Edit:
The german guy is Rainer Radow.
Here is a link to his website, and a few photos from that website.
All image copyrights by Rainer Radow.

https://radow.org/dampfmaschine-kaiserliche-marine.php

https://steamboating.de/kaiser/dampfmaschine-kaiserliche-marine-03-09.php

https://steamboating.de/kaiser/dampfmaschine-kaiserliche-marine-03-10.php

https://steamboating.de/kaiser/dampfmaschine-kaiserliche-marine-03-11.php


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Hi green twin
Now this is realy a complicated cast
Super difficult
Chris

 

[chris123]

Hi green twin
Now this is realy a complicated cast
Super difficult
Chris

Hi green twin
On the drawings that u sendet through
I saw that in the middle section is meant to be a slider
Bud my one is empty
Look
The brass u see is the seal on the bottom of the cast
Regards chris

 

[Steamchick]

So "my one is empty" = the Slide-valve is missing!?
Pistons 1-up and 1-down is a 180 degree crank. - That was what I expected, but from the photos I could not see that. These engines are not "self-starting" if the pistons are at the end of their stroke. They need to be "some angle" past the end of the stroke to start just with Steam. So need a flywheel to carry the motion past the ends of the stroke so they can run fairly slowly.
K2

 

[Steamchick]

Hi Green Twin.
I use condensers on models because they can significantly add performance to the flea-power available.
e.g. in a boat.
If the model is on the bench, running freely but not powering anything, then simply exhausting steam is OK.
But on a boat, with limited water supply to the boiler, a condenser means much longer runs by re-cycling the condensate.

• The Flying Scotsman locomotive needed 2 or 3 "re-fills" between London and Edinburgh... That would have been useless for ships travelling thousands of miles across the sea..
• A condenser can get a "half-a bar" below atmospheric, quite reasonably. This means the exhaust side of the piston empties quicker - and especially in the case of a compound engine, can effectively make the engine a "half-a bar" of pressure more powerful and more efficient.
• A model running at 2 bar (30ppsi) without condenser has a total pressure drop of - 2 bar. Add a condenser and you get and extra 1/2 a bar pressure drop = 25% increase without any more heat input. - That is a crude calculation but should explain the principle for using a condenser. - Most of my models only need 15~20psi, so benefit a lot from a condenser on the exhaust. - Usually just a short coil inside the water -feed tank - so it pre-heats the feed water as well!
• While condensers were a great improvement of the Newcomen engines, (James Watt's idea I think to have a separate condenser?), the application of "high pressure steam" (courtesy of Richard Trevithick?) also benefitted those engines by improving their thermal efficiency as well.

Good stuff!
K2

 

[Charles Lamont]

Steamchick, the normal arrangement of a two cylinder engine, compound or twin, is cranks at 90° (Burrell single-crank compounds excepted). I can't yet make out what these are, but photos earlier in the thread show it is not 180°.

Chris, replacing that slide vave is going to involve some interesting measurements down that trapezoidal hole. I suggest you ask your mate Alan to have a good look round and see if he can't find some of the missing parts lurking somewhere.

 

[GreenTwin]

If the D-valve is missing, you can make another one.
To capture the dimensions of a valve face, I put a piece of clean paper into the hole to where it touches the bottom of the steam chest, then use a slightly dirty finger to rub over the paper, over the ports.

Withdraw the paper, and you can use vernier calipers to measure the ports.
Steam ports are usually 70-80% the width of the associated cylinder on the long axis.

On the short axis, you can create the D-valve based on the port dimensions, and based on the throw of that eccentric.
You could assume a late cutoff for now on that D-valve.

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[chris123]

So "my one is empty" = the Slide-valve is missing!?
Pistons 1-up and 1-down is a 180 degree crank. - That was what I expected, but from the photos I could not see that. These engines are not "self-starting" if the pistons are at the end of their stroke. They need to be "some angle" past the end of the stroke to start just with Steam. So need a flywheel to carry the motion past the ends of the stroke so they can run fairly slowly.
K2

Thank you for the reply
Yes indeed ths slider is missing
And the smaller round hohle serms to be empy aswell
How can i tackle all this without having plans?
I shortly running out of steam bro…
The wheel aswell …
No idea
The arms i got a bit of an idea because fo green twin and charles
Bud still. A brass double block …
I need more if i can get it …
Thank you very much in advance
Best regards chris

 

[GreenTwin]

Its no problem to come up with the dimentions for a D-valve.
We just need the port length (long dimension), the port width (short dimension), the width of the steam chest, the height of the steam chest, the length of the steam chest, the distance from the port face to the centerline of the rod hole.

Typically there is an elevated area in the steam chest called the valve seat.
It would be nice to have the dimensions of the seat length and width.
Typically you want the valve to be as wide as the seat, and you want the valve to overide the seat a bit to prevent wearing a shoulder in the seat.

And there are bridges between the ports.
We need the dimensions of the bridges.

Here is a Stanley 20 hp valve seat and valve.
No problem making something that would work for you engine, in my opinion.
We just need the above dimensions.
We can get you into the ballpark I think and it should work.

You can see the seat in brown, the steam ports are the ones with a smaller width, and the exhaust port which is wider.
We will design the valve based on what you come up with for passage dimensions take from the valve face.

Your valve does not have to be domed like a Stanley; it can be a flat-D, and the rod slot can be open to the top.
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Edit:
Did I mention we need the total eccentric travel, measured from full up to full down, so we know the total valve travel.

 

[Steamchick]

Hi Charles, yes, I understand regular twins use a 90 degree crank - and can self-start with no problem. But the local club's compound twin model I had and ran was a 180 degree crank and did not self-start if the pistons were at the end of stroke, as a result. It also had a large flywheel. It was a model made by Apprentices during the 1930s, and was a model of a real engine from early 20th c. My old photos of this engine are poor at showing the crank configuration, but having steamed it more than a few dozen times it didn't self-start when pistons were at the end of stroke. I always set the HP around half stroke for self-starting...

Not exactly clear in this image...
The 180 degree crank had the HP cylinder directly feeding the LP cylinder through a central valve section of the single cylinder casting, quite like this model. Hence my remarks based on experience of that model. I understood that was necessary where a common steam chest was used as the exhaust chamber of the HP cylinder and Steam chest for the inlet to the other cylinder? - unless a separate intermediate steam store was utilised e.g. large bore transfer pipework? The Stuart Turner Compound twin certainly had a large steam transfer pipe, and a 90 degree crank.

I realise I am often wrong, but have not seen a clear view of the crank of this engine. (Post 65 picture shows darkness, which doesn't show me conclusively what the crank is like. One big-end is hidden by the support strut. Needs better eyes than mine). Probably missed something in the posts? So I defer to those that know better. Sorry if I am wrong. I didn't mean to mislead.
K2

 

[GreenTwin]

The twin steam engines used for electricity generation generally had cranks at 180 degrees, and were not self starting, since they were dedicated units that only had to be started once, and needed to be as smooth in operation as possible for generation purposes.

A twin steam engine in a boat/ship would need cranks at 90 degrees, so as to be self starting.

Looking through my old engravings of vertical steam ship engines, I don't see a flywheel on any ship engine of this style.
Not to say they never had flywheels, but I don't see flywheels on the vertical ship engine engravings, and so I suspect the propeller served as a flywheel in many/most cases.

The launch engine below is a compound that looks much like the one in this thread, with cranks at 90 degrees, and no apparent flywheel.
The mass of the propeller is a flywheel from a functional standpoint.
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[GreenTwin]

Steam ship engine, no apparent flywheel.
I have never seen a flywheel on any marine engine of this style, so if anyone has examples, I would like to see that.
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[GreenTwin]

Twin with cranks at 180 degrees, and a flywheel.
The governor was mounted on this flywheel.
Accurately controlling the speed/frequency was critical on a steam engine used for power generation.
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[GreenTwin]

The Titanic engine had a flywheel of sorts, more of a gear really, but I assume this was only to allow rotation of the engine via the barring engine.
Triple-expansion, 4-cylinder, with two low pressure cylinders, since the diameter of a single low pressure cylinder would be excessive.

 

[Jasonb]

Question is what equipment do you have to mak ethe missing parts and have you made anything like them before

 

[GreenTwin]

See post #46.
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