Author Topic: REVERSING VALVE FOR AIR/STEAM ENGINES  (Read 4588 times)

Online Brian Rupnow

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REVERSING VALVE FOR AIR/STEAM ENGINES
« on: June 23, 2018, 08:19:16 PM »
I was so impressed with the way my new reversing valve worked on my double wobbler that I have to share it. This is by no means an original design, as I was helped by a couple of forum members to figure out exactly how this kind of valve would work. About the only difference in a valve like this working on steam as opposed to air engines, is that the air inlet tubes should be threaded into the main valve block and not just Loctited as I have shown. I know for sure that this reversing valve will work on a wobbler (oscillating) engine. I'm not sure if it will work on a conventionally valved engine like the Cretors Popcorn engine or not.

« Last Edit: June 23, 2018, 08:52:06 PM by Brian Rupnow »

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #1 on: June 23, 2018, 08:22:34 PM »
Three more of the components


« Last Edit: June 23, 2018, 08:55:01 PM by Brian Rupnow »

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #2 on: June 23, 2018, 08:36:42 PM »
And the last three components.


« Last Edit: June 23, 2018, 09:01:35 PM by Brian Rupnow »

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #3 on: June 23, 2018, 08:51:44 PM »
And, if the jpeg files shown aren't clear enough, this download link will get you the drawings as pdf files.
http://www.mediafire.com/file/tddcqq87r5ob79k/REVERSING%20VALVE%20FILES.zip
« Last Edit: June 23, 2018, 08:56:57 PM by Brian Rupnow »

Offline crueby

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #4 on: June 23, 2018, 09:23:26 PM »
Thanks very much for sharing these!

Offline JC54

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #5 on: June 23, 2018, 10:38:00 PM »
Many thanks for your drawings Brian, I have been at Rutland Water (UK) today and spotted a steam launch with a similar designed reversing valve on an oscillating engine. I didn't realize wobblers were used at full size  :shrug:, I thought that they were just for us beginners (ME) to begin with or in Mamod. I will take camera tomorrow and upload pics if anyone interested.   :DrinkPint:

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #6 on: June 27, 2018, 09:53:04 PM »
If anyone builds this reversing valve I have shown, I would really appreciate seeing a build log.---Brian

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #7 on: June 27, 2018, 11:49:53 PM »
Andrew in Australia built one yesterday for use with live steam. He sent me some finished pictures, and it looks great. He has yet to try it, but will let me know the results.--Brian

Offline Ramon

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #8 on: June 28, 2018, 09:40:45 AM »
Hi Brian - thanks for taking the time to draw this design out  :ThumbsUp:

I first did it around the late seventies for two small vee twin oscillators set side by side and running in opposite directions to each other. Destined for a model 'toy' boat that never happened due to the boiler I built for it, having been made from brass  ::) de-zincified within a short time the end plates weeping severely as pressure was applied.

The design I guess is as old as the hills - I think I took it from KN Harris's book in the first instance but even then that was probably repeating it from further back too.

I don't have a build log of mine to share - either that early one or the one I posted for you, but I think the rebuild of the oscillator that this one is on may be of interest so perhaps I'll do that a bit later.

Incidentally - I sold those first two little vee oscillators still in their twin set up at the last aeromodelling swap-meet held at Watford here in the UK. That would be quite some time ago now  but some time back, maybe two three years or so, Jo kindly posted some pics of engines she had taken at a model show. I was absolutely convinced that one of them was one 'side' of my twin set up but try as I might I can't find that pic again.

Regards - Tug
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(a very apt phrase - thanks to a well meaning MEM friend)

Offline Jo

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #9 on: June 28, 2018, 09:54:36 AM »
Incidentally - I sold those first two little vee oscillators still in their twin set up at the last aeromodelling swap-meet held at Watford here in the UK. That would be quite some time ago now  but some time back, maybe two three years or so, Jo kindly posted some pics of engines she had taken at a model show. I was absolutely convinced that one of them was one 'side' of my twin set up but try as I might I can't find that pic again.

Was it this one

Jo
Usus est optimum magister

Offline Ramon

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #10 on: June 28, 2018, 10:05:29 AM »
Thanks Jo but no, not that one - very similar though but then they all do have a similarity eh? .

As I recall mine had the pipework going into small brass manifolds bolted to the side of the standards. They were 'square' too 3/8 bore by 3/8 stroke I think which kept the height quite low. I may, somewhere up the loft have an old photograph from a Forncett day where they whirred away each year on air. I have to go up there later - I'll see if I can find something.

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Jasonb

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #11 on: June 28, 2018, 10:44:45 AM »
Ramon, your restoration of the V twin is still on the boating forum where you posted it before which may save you some typing if you are going to post the rebuild here.

Offline Ramon

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #12 on: June 28, 2018, 10:27:53 PM »
Thanks Jason -  :ThumbsUp:

No luck on  a specific photo but a couple of general ones where you can see it on the table - made for a great distraction in ending up looking at a lot of photos of all sorts of past times  :)

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #13 on: June 28, 2018, 10:45:28 PM »
We all know what curiosity done to the cat. Ever since I designed this reversing valve, I have wondered if it would work on a conventional steam engine or not. Today, due to absolute boredom, I got one of my more conventional steam/air engines down of the shelf and modified it a little bit so I could hook the airline to the exhaust pipe. I didn't think it would work, and I was right.---It didn't. So--it works on wobblers, but not on conventional engines.

Online Brian Rupnow

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #14 on: June 29, 2018, 01:44:53 AM »
The deeper I get into this, the more I learn. The reversing valve will work on both "oscillating" and "piston valve" style engines. It won't work on slide valve engines.

Offline Ramon

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #15 on: June 29, 2018, 07:42:09 AM »

If you think about it Brian this valve changes the direction of inlet of the steam/air. A slide valve engine has a constant direction of pressure and is only reversed by changing the valve position relative to the crank shaft hence the many forms of 'reversing' gear designed over the years, mainly to improve/enhance the cut off.

There was a lovely little inline piston valved twin cylinder model boat engine produced by one of the UK manufacturer at one time. A very neat version of this valve was set between, and integral with, the cylinders giving it a genuine 'forwards to go forward back to go back' capability. (I think that phrase came originally from the old East German DAF car ?) I have no idea who made it - perhaps Jason would know.

It's all been done before - you're just a little late for the party I guess but there's nothing like discovering things for the first time  :)

As they would say over here in ol Suffolk - "jest you keep ona troshin bor, yor dewin a foyne jorb" (Just keep on with the threshing boy, you're doing a fine job)  :ThumbsUp:

Regards - Tug



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(a very apt phrase - thanks to a well meaning MEM friend)

Offline Jasonb

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #16 on: June 29, 2018, 08:44:41 AM »
The other issue with reversing the flow on a slide valve even if you did have the eccentric at 90deg to the crank is that the air/steam would just lift the valve off the port face.

Can't help on the boat engine I'm afraid

Offline crueby

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #17 on: June 29, 2018, 02:35:53 PM »
Actually there is at least one version of a slide valve (d valve) type engine that does do this. The slew and crowd engines on the Marion steam shovels had a central valve that reversed the flow of steam/exhaust passages, and a double layer slide valve that allowed it to work. Here is a cross section with how they did it:

In that pic, the steam is coming in the left hand hole (red in the yellow block) and being directed to the right hand end of the cylinder, pushing the piston left, and the exhaust is directed to the grey hole.

Then, in this next pic, the slide valve is moved to the right, putting the steam to the left of the piston, and the exhaust going out the right of the piston.  There is steam pressure all around the slide valve, holding it down. When the center valve is in the other direction, steam would be directed to the grey hole and exhaust to the red hole, reversing the direction the piston is pushed.


This is not a theoretical thing I thought up, this is actually how the Marion engines worked.

Offline Ramon

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #18 on: June 29, 2018, 03:17:52 PM »
Well 'there you go' Chris - just shows that you can learn something every day no matter how old you are  :ThumbsUp: You'd have to agree though it's not a 'conventional' slide valve - in model terms that is ;) It would be an interesting challenge to make one.

I found a pic earlier of the Perseus engine by Cheddar Models (that is not the engine I was thinking about previously) that apparently has 'slide valves' and a reversing steam/air 'system' set to the side of the cylinders - wonder if that was on a similar principal?

Thanks for the enlightenment Chris

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline crueby

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #19 on: June 29, 2018, 03:20:34 PM »
Well 'there you go' Chris - just shows you can learn something every day no matter how old you are  :ThumbsUp: You'd have to agree though it's not a 'conventional' slide vale - in model terms that is ;) It would be an interesting challenge to make one.

I found a pic earlier of the Perseus engine by Cheddar Models (that is not the engine I was thinking about previously) that has 'slide valves' and a reversing system set to the side of the cylinders - wonder if that was on a similar principal?

Thanks for the enlightenment Chris

Regards - Tug
Later on in my Marion shovel build I'll be making 3 of this style engine, for crowd, slew, and steering. The main hoist engine has a conventional d valve. Only way I figured this one out was by studying thier patent on that valving, which fortunately had plenty of cross section views.

Offline mnay

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Re: REVERSING VALVE FOR AIR/STEAM ENGINES
« Reply #20 on: June 29, 2018, 07:08:05 PM »
Brian,
thanks for sharing the drawings on the reversing valve.  I have a couple of engines I can use it on.

the rest of the group,
I appreciate the info and discussion on valves

Mike