CONWAY 0-4-0 3 1/2" GAUGE LOCO

[cnr6400]

Hi Rich, Here's some more info on the valves I had in mind. These are rated to 1000 psi and 204 deg C continuous but will tolerate much more heat. Years ago many people on the ProBoards forum had success with these valves as regulators on scale locomotives. The valves do take up some room though. I know they will fit virtually any 7 1/4" gauge locomotive. Typical install is by removing the plastic handle, fitting the stem through the smokebox wall and running a lever and operating rod along the outside of the boiler. However, I have seen one install where the stem connected to an in-boiler operating rod like yours. The plumbing inside the smokebox had a lot of turns to do that install though.

Here's a link to the female NPT fitting version:
https://www.swagelok.com/en/catalog/Product/Detail?part=SS-2P4T4

and the male NPT fitting version:
https://www.swagelok.com/en/catalog/Product/Detail?part=SS-2P4T2

Sorry I don't know what these valves cost these days but Swagelok were never cheap - they were absolutely best quality valves and fittings though - used them many times in industry and they went way above and beyond the call of duty. Just food for thought.

[Firebird]

Hi

Thanks cnr6400

I have removed the inner dome and disc from the regulator



I can't see anything wrong or indeed how I could improve the parts.

On the plans



It says body gunmetal, valve stainless steel or gunmetal. I used stainless steel. I am going to make another from bronze.

But just to satisfy myself, before I pull out all the pipework, I am first going to make a blank disc and fix it to the body with some gasket sealant, refit the inner dome and pump it up again. If it holds pressure I then know my pipework is good

Thats the plan anyway

Cheers

Rich

[Firebird]

Hi

Made a disc from bronze and fitted it to the regulator with liquid gasket



Refitted the dome and pumped it up

Same problem. Leaks

<a href="https://www.youtube.com/watch?v=SP6jHP5AEDc" target="_blank">http://www.youtube.com/watch?v=SP6jHP5AEDc</a>

So it must be in the pipework

Cheers

Rich

[Firebird]

Hi

The wet head and super heater came out ok



Followed by the pipe and bush.



I then took out the regulator and decided to start from scratch. I made up an adapter to attach the pump to the regulator and pumped it up. I know the pressure is on the wrong side of the disc but it held ok

Here is the problem

<a href="https://www.youtube.com/watch?v=VJS5QuFwBhs" target="_blank">http://www.youtube.com/watch?v=VJS5QuFwBhs</a>

Cheers

Rich

[crueby]

Is that the regulator body itself that is weeping? Is there a soldered seam there?

[Firebird]

Hi

Yes its the gun metal regulator body casting thats weeping. I had to remove quite a bit of metal from the back of the casting to get it to fit inside the dome. Obviously too much 

Its repairable with a bit of bronze and silver solder

Cheers

Rich

[Kim]

Quite the sleuthing job there, Rich.
That was a lot of work to figure out where the leak was.  But now that you know, hopefully, it can be addressed!
Kim

[Firebird]

Hi Kim

I have to have a think about it now. Whether to try and repair this one or start again with a new/differnt one

Cheers

Rich

[Steamer5]

Hi Rich,
 Good skills!
That’s going to be fun to fix, maybe solder a shaped shim of brass over the whole side?

Cheers Kerrin

[Firebird]

Hi

Kerrin, it would have to be bronze not brass but thats just a detail. I would have to be careful how much I added to the width or the inner dome wouldn't fit again 

Ball valves have been mentioned so I have been searching around google and they seem to be becoming very popular.

What about the tapered cone type ??



The one on the left is one I made some years back as an experiment. I tried it on my beam engine and it worked ok.

The one on the right is a gas tap I think, picked up at a steam fair or market

Cheers

Rich

[cnr6400]

For external valves on the boiler the tapered cone type are OK because they can be removed and fixed if the cone gets worn or "picks up" and jams (which they often do). Internally in the boiler I would not recommend them because of the issue of access to repair them if a problem occurs. Just food for thought.

If you do decide to use the casting-based regulator again I would revise the design from two drilled holes to one hole, large as possible, or fabricate the regulator from two bronze blocks and two copper tubes, or blocks and one tube formed into an oval shape. Fabrication might allow smallest outside size with least leakage risk.

[Firebird]

Hi

Thanks cnr6400 

Cheers

Rich

[cnr6400]

Good luck with it Rich, and do keep us posted!     

[Firebird]

Hi

Thanks again cnr6400 

Well I spent a few days messing about with the regulator, trying to get the disc to seal on the body (I ignored the pinhole leak for now) with no success. I tried wet and dry, lapping, fettling all to no avail 

Looking on the internet it seems a lot of people have had a lot of problems with the stroudley type of regulator. Some people have said that their boiler inspector has allowed the blanking off of this type because of the leaking problem.

I spoke to our club inspector and he is not keen on the blanking off idea. To be honest neither am I. I would prefer the regulator to seal.

Looking into other types of regulator it seems the screw down type is the most preferred. The problem I have here is the front and rear bushes on my boiler are threaded 1/2" x 40 so I could just about get 7/16" through the hole, not enough to get a screw down regulator through. I could drill out the rear bush and silver solder a bigger one in but I don't fancy the idea of doing that for fear of creating more leaks on the back head.

Using ball valves as suggested by cnr6400 is an idea that is becoming very popular with many loco builders. Getting to fit into the boiler is looking difficult. Fitting one into the smoke box is a possibility and I might go down that route on the next loco I build.

So looking at the options I have now It would be best if I could get a regulator into the boiler in its present position.

I have come up with this idea which seems to work. As a test of the idea I have made one from aluminium, not wishing to waste a piece of bronze. It incorporates the cone from the screwdown valve and a cam action.

<a href="https://www.youtube.com/watch?v=K0jrQMikVT0" target="_blank">http://www.youtube.com/watch?v=K0jrQMikVT0</a>

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

More details to follow

Cheers

Rich

[cnr6400]

That design looks better than the Evan version of the Stroudley one, for sure. A great feature is that all the working parts can be removed vertically out the steam dome top for service, and the seat cleaned up with a tool in from the top. That is a major plus. I believe I have seen a similar design regulator in ME or EIM , maybe by Gordon Smith of safety valve fame or by Nigel Bennett of Super D locomotive design fame, but the memory is not so good these days, I could be wrong on the who.

Good thought Rich!