By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

oscillating disc valves

Victorian freelance 5" gauge 4-2-2 with disc valves

All Topics | Latest Posts

Search for:  in Thread Title in  
Bob Clare 124/04/2018 23:58:32
6 forum posts
4 photos

I inherited a box full of dismantled remains some years ago and having finished rebuilding a Hielan Lassie, I dragged it out last year. I contacted several venerable sources York, Science Museum, SMEE etc. about this valve system and its use on locomotives. The universal answer was "never heard of this use for oscillating valves".

So my opening question for readers is:

Has anyone ever seen or heard of such a locomotive or model? If so, any info will help with the rebuild and if not then I may have a rare relic here.


John Reese25/04/2018 22:29:15
824 forum posts

How about more info. Never heard of that type of valve and you got my curiosity up. Do you have photos or sketches you could post?

Bob Clare 126/04/2018 00:10:51
6 forum posts
4 photos

This forum system has beaten me - how do you paste a Word page containing photos?


Hopper26/04/2018 04:02:54
4152 forum posts
89 photos

Instructions on how to post photos on this site are here **LINK**

I think you will have to use the individial pics out of the Word page, not the whole page unless you can save it as a JPEG or something like that.

I think your question is one of those that needs pics in order to work at all. Sounds like an interesting machine from your description, and certainly not a common one.

Edited By Hopper on 26/04/2018 04:05:28

Bob Clare 101/05/2018 00:50:55
6 forum posts
4 photos

eamus 5 inch as found engine.jpg

First attempt to add photo to posting. Did it work? if so I'll try sending the others i.s. the oscillating disc valve set up.

Hopper01/05/2018 01:09:00
4152 forum posts
89 photos

Yes, pic looks good. Looks like an interesting project.

Bob Clare 101/05/2018 23:59:52
6 forum posts
4 photos

Here are 2 shots of the disc valve components (I hope!).eamus valves displayed.jpg

eamus 4-2-2 stam chest and valves.jpg

IanT02/05/2018 15:01:24
1443 forum posts
141 photos

A very interesting vintage locomotive Bob, so I thought I'd 'Bump' this thread back into visible space...

But some more photos of the engine would be useful too - an 'underneath' shot of the engine might help satisfy my curiosity as to how this actually worked!




Phil H102/05/2018 15:57:17
233 forum posts
25 photos

Bob, I believe that I have seen an oscillating valve similar to your example on a simplified beam engine but not a locomotive. The beam engine design was published in a magazine like Home Mechanic or similar.

The idea is clearly less complicated but I am sure that a model locomotive builder will be along to discuss why standard Stephensons valve gear with slide valves would be better.

Phil H

Bob Clare 103/05/2018 00:41:12
6 forum posts
4 photos

5 steam chest dismantled.jpg

Ian I'll need to mount the engine upside down in some sort of cradle to take the photos you suggest. I'll have a go tomorrow. In the meantime here's a shot of the dismantled steam chest with the valves beneath in place which might help a bit. Do you know whether one can upload video shots onto the forum? I've got some action clips of the early trials to see if the wheels would turn at all. They did under 40psi air both forwards and backwards.

Phil - yes I'm aware of the use of this valve design principal on Victorian mill engines etc. but none of the experts I've talked to (SMEE, York, Science Museum etc.) have come across either model or full scale steam locomotives using this design principle.

Hopper03/05/2018 00:55:09
4152 forum posts
89 photos

Post your video on YouTube and then post a link to it on here using the little Youtube Icon at the top of the post window, above where you type your message.

Intriguing looking engine, though I can't quite figure how the first two pics relate to the last one you posted. Either way, never seen anything like it in my limited model loco experience.

John Baguley03/05/2018 08:22:29
452 forum posts
48 photos

It looks to me that the cylinders are actually conventional slide valves but the valves are round instead of rectangular. LBSC used round valves on his Ayesha. The last photo shows the round valves connected to the valve rods.

The round parts that I think you are thinking are the valves are actually the port faces and the ports are curved to match the circular valve. The large central hole is the exhaust port Are you sure that these rotate? It's possible that the port discs were made separately for ease of manufacture and remain stationary once in position. I can't see a reason at the moment why they would need to rotate. Are there grooves under the port face to connect the ports to the steam ports drilled in the cylinder?

The loco may well have conventional valve gear such as Stephensons.


Edited By John Baguley on 03/05/2018 08:23:16

Edited By John Baguley on 03/05/2018 08:25:11

Bob Clare 105/05/2018 00:12:05
6 forum posts
4 photos

Never used the "social media so the advice on video transfer is lost on me.

John, essentially you are quite correct. The only "oscillation" occurs when the reversing gear in the cab is used; this rotates the discs so "oscillating " was the wrong term to use. Sorry about that but I'm only a simple microbiologist.

If you look and the coloured image in my 1st. May posting you can see the external part of the mechanism first with the fixed face in the block with the rotating disc removed and second with it in place. I failed to take appropriate shots of this and I've now reassembled the steam chest complete with pistons, valves etc. In the black & white shot the valves can be seen and these are recessed to take an inner circular component which is spring loaded from beneath to keep the face in contact with the disc.

This system avoids all the set-up problems and engineering requirements of Walschaerts, Baker etc. systems. It works OK on air but under steam? I don't yet know.

If I have to strip the steam chest again, I'll make sure I take the right photos!


All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Allendale Electronics
Eccentric July 5 2018
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest