Western Rivers Steamboat Engines

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Dick_Morris
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Western Rivers Steamboat Engines

Post by Dick_Morris »

It's not riding scale railroads, but it is live steam.

Many years ago, after a cruise on the Delta Queen, I started modeling a pair of stern wheel steamboat engines. I collected some materials and made some parts, including over 100 arms for the paddle wheel, but I became overwhelmed by the need for complex castings or fabrications of some parts and I set it aside for later. Fast forward by 40 years and with 3D printing and investment casting available I'm ready to make another start.

There isn't a lot of technical information available on the engines. I've seen two models. Sam Hodgeson designed an engine and sold the drawings, but the emphasis was on a working, rather than scale model. I also saw a beautiful model in about 1978 at a Model Engineering Exhibition in London. Most of the drawings I found for this style of engine were in a single I.C.S. textbook. I was hopeful that new information had appeared on the Internet over the years, but a search revealed the best information was a web page that I created 21 years ago. http://www.alaska.net/~rmorris/steamboat1.htm

This engraving of this engine with California cut-off is what I will generally follow. The appearance pleases me and when running there is a lot of activity with levers lifting the poppet valves and adjustable wedges controlling the cut-off.

I will be creating the parts first by printing them in a cheap resin to check fit, appearance, and mark where I want a machining allowance. When I'm happy, I will cast them in bronze. The cylinder block is the first mock-up component. It is exactly 6" long. Although the bore would be 1" if it was intended to do work, I will probably use 3/4" or 7/8" to conserve steam/air for operating it. It's the biggest component and I had to make it in three parts to fit the size limitations of my printer.

I'm currently working on drawings for the chambers for the valves. The design in each of the prototype drawings is a bit different and none have a full set of views, so I'm having to use some imagination. I hae a full day invested and I still have quite a ways to go. The internal passages, compound curves, and lack of complete drawings are making it quite a challenge. I'm going to include balanced poppet valves and O-rings for the sealing surfaces.
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Schellhorn-Albrecht Engine.jpg
20210807_203136 reduced.jpg
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NP317
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Re: Western Rivers Steamboat Engines

Post by NP317 »

Studying the engine drawing I cannot figure out how the valve mechanism works.
In part because I don't know what/where the external control rods are/go to.

I just looked at your referenced web page and I suspect my questions will be answered there.

Very interesting project.
RussN
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Dick_Morris
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Re: Western Rivers Steamboat Engines

Post by Dick_Morris »

One source for the ICS text is "The Elements of Marine Engineering," Volume II, dated 1900. As was their practice, ICS republished the same material in individual pamphlet type lessons and a number of books.

The web page gives a little bit, but doesn't explain it well. If you're curious, I can send a copy of the relevant pages of the text.

Some engines are made with slide and piston valves, but they aren't as interesting because they don't have all the parts flailing about where they can be seen. For the poppet valve engines there are several of variations on how the cut-off is attained.

For the California cut-off, motion to actuate the valves can be from cams or eccentrics (Delta Queen) on the wheel shaft or by an "inside cam" (I believe that's the right name). The inside cam takes its motion from the pitman (connecting rod) rather than the wheel shaft. Through rocker arms, that valve motion lift and open the valve levers.

Reversing can be done with spiders/gabs or on the Delta Queen with a motion similar to Stephenson, although this gives only reversing, not cut-off.

For the California cut-off, the cut-off of steam is done by overriding the lift of the intake poppet valves from the levers by sliding a wedge shaped shoe that is on top of the lever. When slid out from between the top of the level and valve stem the valve drops under pressure of a spring in the tower with a satisfying thunk. The point in the stroke where the shoe is moved determines cut-off of steam. The motion for the cut-off comes from an oscillating lever actuated by the crosshead.

This explanation along with the web page might make it clearer. Despite all the parts moving around it's actually quite simple when you can watch it. I understood everything going on with the Delta Queen by watching it for about five minutes.

I gave Charlie Dockstader a copy of the text about 30 years ago and he added several types of Western Rivers valve gear to his software. I'll have to look at it and see if the simulation makes the operation clear.
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Dick_Morris
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Re: Western Rivers Steamboat Engines

Post by Dick_Morris »

California cut-off is WRSBoatC in Charlie's valve gear program. (http://jf2.com/bcwrr/Dockstader-Valve-Gear.html) The cut-off function is demonstrated, but is caused by using the reverse slider. Forward and reverse using the gab gear isn't operational, probably because cut-off and reversing are two different controls in this style of engine instead of combined as is typically done in other valve gear. In the simulator the intake and exhaust are shown one above the other.
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NP317
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Re: Western Rivers Steamboat Engines

Post by NP317 »

Dick:
Many Thanks for the additional information.
Worth a study.
RussN
Sandiapaul
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Re: Western Rivers Steamboat Engines

Post by Sandiapaul »

Conrad Milster wrote a few articles in Model Engineer back in the 1970's, maybe 60's on these. Might be worth looking into?
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Dick_Morris
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Re: Western Rivers Steamboat Engines

Post by Dick_Morris »

I had that ME at one time, but donated all of them several years ago. I feel pretty comfortable about the technology, the biggest challenge is to draw/print/cast a practical valve chamber.

I've been making some parts and while doing some casting yesterday I included a few steamboat engine parts. I also found the pitman arms that I made 35 years ago in the garage within a couple of feet from where I thought they were.
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20210813_151954[1].jpg
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Dick_Morris
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Re: Western Rivers Steamboat Engines

Post by Dick_Morris »

Mocking up some parts in 3D printed plastic to see how they fit together.

00-90, but they looked a lot bigger on the monitor when I was drawing them!
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20210819_193024.jpg
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