Penn Valve Gear???

[paul gough]

Hello Everyone, I came across an interesting video of an oscillating engine with a slide valve operated by Penn's valve gear in Crofton Pumping Station. The only other information I have thus far found is an article on the American Society of Mechanical Engineers site about the steamboat 'Diesbar'. I wonder if there are any knowledgeable souls who would be able to provide further information on this valve gear or models with it, especially a diagram showing its layout etc. Regards, Paul Gough.

[crueby]

Hi Paul,
A while back I had some discussions about that engine with Michael here on the forum, he pointed me at a book by Josef Reineck that has slightly simplifed plans for a model of that engine. There are some videos online of the real one running. Here is a link to the book (in German)
https://www.amazon.com/Dampf-44-Die-Diesbar-Schiffsdampfmaschine/dp/3788341173
Its a very interesting valve design - I have not worked through the diagrams close enough to really understand the reversing part of it yet, but the book has plans for all the parts.
Chris

[Jasonb]

This video has a model of the valve gear

<a href="https://www.youtube.com/watch?v=yOmD0vXOiPE" target="_blank">http://www.youtube.com/watch?v=yOmD0vXOiPE</a>

[Admiral_dk]

The video show it well - thank you Jason 

Per

[paul gough]

Thank you Jason and Chris, These give me something more to work with. I saw a video quite a while ago of a little slide valve oscillating engine by Elmer Verberg, sorry I don't remember its name and I hope I got his name right. It came into my mind that an adaptation of his engine with a 'Penn' like valve gear might be a nice little diversion for a fossilising brain and fit in with my minute workshop and Sherline machine.
Any further documentation on this valve gear and the engines would be much appreciated, I can usually plumb the meaning, (JUST!), if there happens to be something written in French or German, even though it is an English design as far as I know. Again thanks guys, as is usual our members generosity and knowledge is gold standard! Regards, Paul Gough.

[Jasonb]

The first image of the 1890 engine looks promising

https://gracesguide.co.uk/John_Penn_and_Sons

[Michael S.]

Hello Paul,

Here are a few pictures of the engine.
Google tried to translate the description.
There is a Netherlands blueprint and I think it is a similar control of the cylinder. I only have the blueprint on paper.

Greetings Michael

[paul gough]

Thank you Michael S. There are some confusing attributes in all the information flowing to me. Your drawing appears to be two eccentrics and something similar to Stephensons valve gear, the stationary engine in the video shows one eccentric but I am not sure it is reversable but there is another sheave on the left side of the crankshaft without gear attatched, maybe for setting up for opposite rotation. The 'Diesbar' engine I assume is reversable but has one eccentric per cylinder, though there is an eccentric disc next to the actual eccentric. The valve drive seems on the engines seems similar to the McOnie engine, but it is the reversing/variable cut off part of the gear that I am finding difficulty in coming to grips with. As it is now 5am here I need to go to bed, my brain is hurting.
Chris, I placed an order for the book, thanks again for passing on the details. Regards, Paul Gough.

[Michael S.]

Yes, now I notice it too. The engine of the "Diesbar" has an eccentric and the other engine has 2 eccentrics.

<a href="https://www.youtube.com/watch?v=YZVwQVIXlh8" target="_blank">http://www.youtube.com/watch?v=YZVwQVIXlh8</a>


<a href="https://www.youtube.com/watch?v=gRT1-WICJUc" target="_blank">http://www.youtube.com/watch?v=gRT1-WICJUc</a>

[crueby]

Yes, the Diesbar uses a slip eccentric to do the reversing, which makes it a little harder to understand just from the drawings. That book shows the version just like the Diesbar.  Michael, glad you posted those videos, I was  still looking for them again.

[Michael S.]

The eccentric of the steam engine is loosely attached to the crankshaft.
The reversal of the engine must be carried out using an extra mechanism, a “release lever” ( Ausklinkhebel ). The picture is from the book of the model of the "Diesbar".

Michael

[paul gough]

Thank you very much Michael, this is a great help in coming to grips with this engines valve gear arrangement. I notice the PD Krippen has a similar engine and gear. What still is unclear is the purpose of the large circular plates adjacent to the eccentrics and set at what appears to be 180 degrees. I speculate, are they part of the slip eccentric drive with the plates contributing to some form of balance/counter weight to assist the operator when manually operating the valves in a reversing manouver??? I eagerly await the arrival of the book. Regards, Paul Gough.

[Michael S.]

Hello Paul,

Since I can't explain this to you straight away, I just called a machinist from the Dresden Steamboat Company and asked him about the Diesbar's steam engine. The discs are initially compensating weights and also carry two screws for the stops for the sliding eccentric. The stops are adjustable.
Only the Diesbar's steam engine was built strictly according to Penn's patent.
All other steam engines in the Dresden fleet are a mixture of Stephenson and Penn. These are engines that were designed in Germany.

Greetings Michael

[paul gough]

Michael, Again many thanks for your initiative in clarifying the purpose of the 'discs'. I truely wish I could get to see these astonishingly elegant and beautiful vessels with their endearing 'wobbly' engines. May they all last another 100 years. Regards, Paul Gough.

[Zephyrin]

There's a complete description and drawing of a model 2-cylinder oscillating engine, very similar to the 1890 Penn engine, in KN Harris's book, "model stationary and marine engines", with steam distribution via an eccentrically-driven oscillating disk.