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Discussion Starter · #1 ·
I think I may have made my own valve gear using a simulation and physics game called Algodoo. I'm thinking of calling it Chernisky Valve Gear.

Here's what it looks like...


Neutral
Water Slope Rectangle Plot Line


Forward
Water Slope Rectangle Plot Line


Reverse
Water Azure Rectangle Sky Slope


Would this set up actually work if it was made?
 

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Gosh, hard to say, at least for me. Maybe you should try building one! You could probably start with just seeing if the mechanism works rather than attempt to make some pistons and valves.
 

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Accucraft Ruby, Accucraft 1:20.3
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It looks like it will cause the valve to move in a be predictable motion. If your modeling software is able to simulate the function and it behaves, the hard part will be crafting it to function as designed. Computer programs usually don't incorporate slop that you get in the real world.

The concern I see for the longevity of the system is the sliding on the shifter with every stroke takes the load of moving the valve. I would explore the idea of a roller in that track rather than just a pin in a slot.
 

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Alexis,
Welcome to MLS.
During the age of steam there were all types of valve gears invented, and maybe someone even tried what you are imagining, but found it to be not as good as the 'usual' types.
Anyway, good for you to try.
Can you please use the software to now show how it works with the wheels rotated 90º, 180º and 270º so that we can see it with the cylinder and valve in those potions and check all the rotating parts of your gear.
All the best,
David Leech, Canada
 

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Discussion Starter · #5 ·
Alexis,
Welcome to MLS.
During the age of steam there were all types of valve gears invented, and maybe someone even tried what you are imagining, but found it to be not as good as the 'usual' types.
Anyway, good for you to try.
Can you please use the software to now show how it works with the wheels rotated 90º, 180º and 270º so that we can see it with the cylinder and valve in those potions and check all the rotating parts of your gear.
All the best,
David Leech, Canada
I had a recording. but it' gone right now. I plan on remaking it in some cad software when I can.
 

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What is your purpose i designing this valve gear? What do you want to solve?

As David points out, there existed a pleothora of valve gear designs during the developement of steam engines. They all have their merits and compromises.

Perhaps the most obvious example is the Stephenson's valve gear compared to the Allen type, which was designed to specifically give the steam admission cycle a different charracteristic. I'm to tired to recollect the purpose now.

I put the question to ChatGTP "What respective merits and compromises characterises the Stephenson steam engine valve gear compared to the Allen type?"

ChatGTP answered "
The Stephenson valve gear, also known as the "link motion," is a type of valve gear used on steam engines to control the admission of steam into the cylinders. It is characterized by its simplicity and reliability. One of its key advantages is that it can be easily adjusted to compensate for wear on the valve gear and engine components. However, it is not as efficient as other types of valve gear, such as the Walschaerts valve gear, and it can be more difficult to set up and maintain.

The Allen type valve gear is a type of valve gear used on steam engines to control the admission of steam into the cylinders. It is characterized by its efficiency, as it allows the engine to operate at higher speeds and with less steam. One of the main disadvantages of the Allen type is that it is more complex and difficult to set up and maintain compared to the Stephenson type.

In summary, the Stephenson valve gear is simpler and more reliable, but less efficient compared to the Allen type valve gear which is more efficient but also more complex and difficult to maintain."

However, normally I can give you a much shorter and more to the point answer as to the merits of the Allen type valve gear.

Aster has modelled the Preussian small T3 locomotive that was produced in huge numbers beginning in the late 19th century. In spite of the complicated design Allan type valve gear was used. It's fascinating watching the models valve gear work. Photo of Aster model.
Train Vehicle Wheel Steam engine Rolling stock


A photo of the prototype from Wikipedia.
Train Wheel Vehicle Rolling stock Rolling


According to ChatGTP "The Allen valve gear was developed by James Naysmyth Allen in the early 1900s. He first patented the design in 1901, and it was first used on a steam engine in 1903.

The Walschaerts valve gear, also known as the Walschaerts system, was developed by Belgian engineer Egide Walschaerts in 1844. It was first used on a steam engine in 1849, and quickly became popular due to its improved efficiency and ease of adjustment compared to other types of valve gear at the time."

So the first T3 locomotives produced in 1882 (Wikipedia) must have used some other type of valve gear. The advantage of steam economy with the Allen system at greater speeds doesn't make sense as a reason for choosing it for the T3 locomotive design, since I believe maximum allowed operating speed was 30km/h, later raised to 45km/h. (30mph)

Operating the Aster model at some sort of prototypical speed seems to be a true challenge. :LOL:

Regner made a very simple live steam design of the T3 - later BR89 - with the simplest valve gear I've ever seen. But the valve has no overlap / cut off, and is not reversible. Instead a separate valve is used to reverse the flow of steam to change direction.

Train Rolling stock Vehicle Wheel Steam engine


I'm not out to put your idea down, but there is an obvious chance your design already exists. Have you checked?
 

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I am not familiar with the design of what was called Southern valve gear but I wonder if your design isn't related to it. As I dont have any drawings of it i can't check. It also recals the simplified valve gear used on Orenstein and Kopel contractor's locomotives in Germany. In this the link was vertical though.
du-bousquetaire
 

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Something is misinformation in chatGTP , Allan valve gear was in common use in the 1880s, Beyer Peacock used it in the 1890s on the NSW railways "P" class then. principal difference from Stephenson Gear is the straight link slot, which hangs on 2 suspension links and simplified maintenance was one of its benefits claimed.
 
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