Mystery steam engine

[Richard Hed]

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...
View attachment 163678
View attachment 163682
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.
View attachment 163683
View attachment 163684
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

Whoa Nellie, your steam photo clearly shows valves in the center of the engine but the illustrations show the valves on the outside. The OPs engine shows valves on inside as stated by someone above. So do you still have the engine? Do you know what it looks like when the cap is taken off the valves? Looks to me like your engine is very close to the OPs.

 

[Steamchick]

Hi Richard, I can access the engine, but not immediately, as another club member has it in his charge.
But as a generator engine it has a 180 deg crank, not a 90 degree crank.
The illustration drawings were of the Stuart compound twin, based on the simple twin, which was based on 2 singles....
I understood - perhaps wrongly? - that a compound could feed directly from one cylinder to another directly if the valve timing and pistons were timed together (e.g. With the 180 deg crank). But for a 90 deg crank, the timing is too far apart, so interposing pipework, or a steam reservoir, was needed to store steam from the exhaust of one cylinder and open inlet of the next. This steam (reserve) could also have extra heat added to improve power. The Stuart has such pipework (and they should be lagged to conserve heat). Hence the photos I posted.

Sorry for the inadequate explanation before.
K2

 

[Richard Hed]

Hi Richard, I can access the engine, but not immediately, as another club member has it in his charge.
But as a generator engine it has a 180 deg crank, not a 90 degree crank.
The illustration drawings were of the Stuart compound twin, based on the simple twin, which was based on 2 singles....
I understood - perhaps wrongly? - that a compound could feed directly from one cylinder to another directly if the valve timing and pistons were timed together (e.g. With the 180 deg crank). But for a 90 deg crank, the timing is too far apart, so interposing pipework, or a steam reservoir, was needed to store steam from the exhaust of one cylinder and open inlet of the next. This steam (reserve) could also have extra heat added to improve power. The Stuart has such pipework (and they should be lagged to conserve heat). Hence the photos I posted.

Sorry for the inadequate explanation before.
K2

But that is not what I was getting at. Most twins have the valves on the outside, yours has the valves on the inside. The OPs valves are on the inside. I'm wondering if the two are close relatives?

 

[GreenTwin]

The original-poster (OP) engine has a lot of fine details in it that I don't normally see in model engine kits.
Makes me wonder if it was used for a small steam launch or something, otherwise why include all the functional details like pressure relief valves on top the cylinders, etc.

It also would seem the OP engine is pretty old; dating back to the 1920's or before.
Just guessing outloud.
.

 

[Richard Hed]

Ha! I was just wondering what the IDs and throw is. Lookt thru the post and didn't find it. Did I miss it?

 

[Jasonb]

There are a few models that do have pressure relief valves rather than drain cocks. The most popular is the Boulton triple expansion.

The nearest model to this layout that I can think of is the Muncaster that I mentioned earlier which has its valves between the cylinders, piston for HP and Slide for LP

 

[GreenTwin]

The OP engine has the old-school nuts on it.
Extra height nuts, flat on the bottom, rounded on top edge.
Generally don't see the tall nuts on model steam engines these days unless they are deliberately made that way.

If you see an engine with modern form fasteners, then that immediately moves the engine to a certain date/year range as far as when it was manufactured/constructed.
.

 

[Jasonb]

modern ones are usually stamped out

You can still buy the single chamfer fully machined ones, I use them on all my engines in metric now but have used BA in the past and I think Americam Model Engineering has them in small UNC sizes.

 

[GreenTwin]

So I am guessing from the fasteners pre-1930 ?
.

 

[Richard Hed]

You all are great detectives. What y'all point out is so clever, but I would not have noticed lest you pointed it out.

 

[Richard Hed]

There are a few models that do have pressure relief valves rather than drain cocks. The most popular is the Boulton triple expansion.

View attachment 163708

The nearest model to this layout that I can think of is the Muncaster that I mentioned earlier which has its valves between the cylinders, piston for HP and Slide for LP

View attachment 163707

Would that cylinder valve be made from bronze? I understand bronze wears better and that cylinder valves wear out faster than slides. Is it possible to put a rubber gasket type seal in the cylinder valve?

 

[Jasonb]

Most models tend to use Bronze or gun metal for the slide valve.

As room is limited it is more likely to be the type with adjusting nuts at either end than what you see on a lot of models where the "nut" is actually a cross bar in a slot

 

[Richard Hed]

Most models tend to use Bronze or gun metal for the slide valve.

As room is limited it is more likely to be the type with adjusting nuts at either end than what you see on a lot of models where the "nut" is actually a cross bar in a slot

I am familiar with the D slide type, but the cylinder type I only know a bit about.

 

[GreenTwin]

The saying is "D-valves wear in, piston valves wear out".
A D-valve is self-adjusting for wear, since it floats on the valve rod and can move up and down.
The pressure on the back of the D-valve holds it against the valve face, which is good as far as getting a good seal, but bad as far as excessive wear, especially for pressures above about 100 psi.

A D-valve does not like superheated steam, but a piston valve can handle it fine, and since a piston valve is balanced, it can be operated with little force even at high pressures such as 250 psi or higher.
I have seen some Stanley steam car engines recast from D-valve to piston valve, and this saves a lot of wear and tear not only on the valves, but on the entire valvegear.

The cores required for a piston valve are a lot more complex I think than for a D-valve.
The piston valves I have seen on full sized engines have piston rings, and I think one of the problems with piston valves is snagging a ring on the port.

I think piston valves became pretty standard on locomotives at some point late in their evolution.
.

 

[GreenTwin]

They did make balanced D-valves, which relieved most of the pressure off the back of the valve.
Here is a balanced D-valve I made for the a bottle engine design.
Spring loaded, and a ring goes in the slot.
The cap rides against the steam chest cover, and the top of the D has a hole in it to relieve pressure in the cylindrical area.
This is based on one of the old designs, not my design.
.

 

[chris123]

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.
.
Edit:
Did I mention we need the total eccentric travel, measured from full up to full down, so we know

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

hi jason

Im into ic engines thats why i not know much about steam
I got lathe and miller and rotary
And lots of equipment
I can make parts to drawings bud with
Steam i dont know what is needet
Best regards chris

the total valve travel.

There is another reason condensers are put on steam engines you may not be aware of. Around 1909, Chicago, having such cold times in the winter and so many steam cars driving around, caused a fog so heavy one could not see in the streets even during the day. So Chicago passt a law requiring condensers. So followed many other cities. Then, of course, they began to realize the benefits of one as you state above.

 

[chris123]

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

Hi jason
I got lathe. Miller and rotary lots of equipment
Im into ic engines thats why i dont know much about steam
Can make parts to drawings
With steam i dont know whats needed
Best regards chris

 

[chris123]

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.
.
Edit:
Did I mention we need the total eccentric travel, measured from full up to full down, so we know the total valve travel.

Thank you green twin i start measuring
Chris

 

[chris123]

There are a few models that do have pressure relief valves rather than drain cocks. The most popular is the Boulton triple expansion.

View attachment 163708

The nearest model to this layout that I can think of is the Muncaster that I mentioned earlier which has its valves between the cylinders, piston for HP and Slide for LP

View attachment 163707

Thank you green twin i start measuring
Chris

Thank you green twin i start measuring
Chris

Thank you green twin i start measuring
Chris

Sorry I didnt got it 3x
Anyway
I shot better pics from the inside before i start so u can see again
If ok i start measure

Thank you green twin i start measuring
Chris

see in the small one are hohles
The big triangle is round inside
Tegards chris

 

[chris123]

Sorry I didnt got it 3x
Anyway
I shot better pics from the inside before i start so u can see again
If ok i start measure

see in the small one are hohles
The big triangle is round inside
Tegards chris

More pics