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What Regulator type.

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James Roberts 404/02/2018 17:17:36
20 forum posts
Evening all,

I'm looking at building a Holmside and getting a chunk of the castings from Reeves or Blackgates.
I see that with Reeves there is an option of slide Valve or Stroudley type regulators.
Which won would be considered the better.
To my limited knowledge and the research I've done the Slide valve should be as the steam pressure helps seal the regulator when it's shut and they shut more completely if that makes sense.
I've read that disk type regs can be hard to get to seal properly to pass the hydraulic test.
Any thought greatfully received.

Edited By James Roberts 4 on 04/02/2018 17:18:45

Bruno Taylor04/02/2018 17:52:19
48 forum posts
14 photos

Hi James,

I will upset a few by saying niether. I have built both Stroudley and disc type. Both leak. I have now converted to a simple screw down type. Easy to make and dont leak. Most useful at boiler test time.



David Wasson04/02/2018 22:14:20
146 forum posts
42 photos

My vote is for the screw down type, especially for a beginner. It has the fewest parts, easy to make, and seals tight 100%.


Clive India05/02/2018 10:38:06
213 forum posts

Posted by Bruno Taylor on 04/02/2018 17:52:19:Hi James,I will upset a few by saying niether. I have built both Stroudley and disc type. Both leak. I have now converted to a simple screw down type. Easy to make and dont leak. Most useful at boiler test time. Regards Bruno

Posted by David Wasson on 04/02/2018 22:14:20:My vote is for the screw down type, especially for a beginner. It has the fewest parts, easy to make, and seals tight 100%. David

+25 from me!

James Roberts 405/02/2018 12:38:54
20 forum posts
OK great thanks for the advice.
Please bear with me for the next bit I'm new.
As this won't be in my drawings where do I find drawings for one, just google it?
Is it easy to incorporate a different type reg into the loco?
David Wasson06/02/2018 02:04:06
146 forum posts
42 photos

Attached should be drawings for two screw down regulators. Martin called them pin valve regulators. The larger regulator has it's dry steam feed from the tube that is pointed upward. This tube would go up into the steam dome. This is the type that was used on Evans' Super Simplex. This is the better design of the two.

If you don't have a steam dome, the smaller regulator might work. It gets it's "dry steam" through the pattern of holes drilled into the top of the regulator tube. But, it is easy for boiler water to splash into this pattern of holes. This regulator, along with many other boiler fittings, was described in Vol #3228 of ME.

The crossed drilled pin that connects the valve spindle to the "handle" spindle, is buried in a counter bore inside the threaded center part. This is so if this pin ever worked it's way out, or loose, it would be captured in the counter bore. It would be not good if the regulator was open, and the pin came loose! Take the extra time to make the center part exactly like the drawing.

super simplex regulator - jpg.jpg

regulator - evans boiler fittings vol 3228.jpg


Edited By David Wasson on 06/02/2018 02:05:51

Edited By David Wasson on 06/02/2018 02:07:31

James Roberts 406/02/2018 09:52:56
20 forum posts
Great, thanks for that David. The Holmside looks to have a steam dome so I'll be able to do the top one with any luck.
Balljoint06/02/2018 13:28:09
37 forum posts
12 photos

Hi James

just a word of warning, if you do use the Simplex design, do not use brass for the regulator tube, it will dezincify over time inside the boiler.

I have just had to replace 2 simplex regulators with this problem. I have made the replacements using stainless steel tube.


norman royds 206/02/2018 16:31:23
48 forum posts

hi james just reading your post about dezincification and wondering about it history. and would this include brazed boiler regards norm

Neil Wyatt06/02/2018 17:09:03
18721 forum posts
727 photos
80 articles
Posted by norman royds 2 on 06/02/2018 16:31:23:

hi james just reading your post about dezincification and wondering about it history. and would this include brazed boiler regards norm

Yes it can affect boilers or bushes made out of brass.


David Wasson06/02/2018 22:57:03
146 forum posts
42 photos

Hi James,

Yes, do use brass on any part of the regulator. Stainless steel, bronze or phosphor bronze only. Brass should also not be used for any of the boiler bushings. Use bronze or phosphor bronze. I used aluminum bronze on the solid parts of my regulator and stainless for the tube and everything else. Aluminum bronze is okay, but, it is not easily silver soldered.

If the solid piece that the valve screws into has a few extra tapped holes for mounting it inside the tube, you can adjust it's position for exactly where the regulator handle will close the valve. The thread for the valve can be right or left handed, depending on how you want the handle to move to open the steam valve.

Attached should be a few photos of the part of the regulator in my Super Simplex.

dscn1367 - reduced 6.jpg

dscn1368 - reduced 7.jpg

dscn1369 - reduced 8.jpg

dscn1370 - reduced 5.jpg


James Roberts 407/02/2018 19:45:01
20 forum posts
Hi David,

Thanks again very helpful.
julian atkins07/02/2018 21:31:56
1239 forum posts
353 photos

Hi James,

I have never made a screw down regulator. They were rather frowned upon when I started this lark because they gave poor regulation of the steam plus a non prototypical angle of opening for the regulator handle, plus if not eased off after a steam up would seize up on cooling down.

The Martin Evans shape of the screw down valve conical end is not optimal for graduated regulator opening.

I am surprised no one has yet mentioned the use of modern gas pipe valves. There would be ample room in a 7.5"g loco such as Holmside with a dome to fit one. They are quite common in miniature locos these days. Far too modern for me, but then I am a bit of a dinosaur!



David Wasson07/02/2018 23:02:08
146 forum posts
42 photos

Hi Julian,

Yes, there are probably more "correct" regulators than a screw down type. I guess we need someone to post a few more drawings and photos. For ease of construction, the screw down type is pretty simple and effective and does not leak.

I'm not sure what you mean by "prototypical angle" of opening. If you mean, where the handle comes to rest when it is open or closed, if you add a few more tapped holes, like I did, on the threaded part, the angle of the handle can almost be set anywhere you want.

Yes, it is true, you should certainly open this type of valve before everything has cooled down after running. This is actually my normal procedure for all of my valves, not just the regulator. I recommend that every one should do the same.



Edited By David Wasson on 07/02/2018 23:02:41

James Roberts 407/02/2018 23:25:37
20 forum posts
Hi Julian,

What type of gas pipe valve do people use? I'm not that up on gas fittings, the only one I know of is the isolation valve wil the big flat handle that turns through 90?.
duncan webster08/02/2018 11:49:58
3445 forum posts
63 photos

If a screw down regulator had a flat face you would need to open it by 1/4 diameter to get full area opening, allowing for a 90 degree point my sums suggest this increases to nearly half. Taking the above example with a 3/8 bore you need 3/16 lift, which with a 3/8 BSW 16 tpi thread is 3 turns. Fortunately you don't need anything like full opening, but it can be seen that taking off the pointy bit to say 5/16 diameter would reduce the opening you do need substantially.

David Wasson09/02/2018 00:59:37
146 forum posts
42 photos

When in use, the regulator I built above, is hardly ever open more than 1/4" turn, usually much less. The thread is a 1/2" x 13 tpi.


Brian Baker 109/02/2018 08:04:47
165 forum posts
34 photos

I would suggest using a high pressure (the type with a gland on the operating spindle), stainless steel ball valve.

it would easily fit into the dome, and give you a leak free silky regulator, and a very controllable loco.

I have decided that I will never use any other type.



John Baguley09/02/2018 08:51:59
488 forum posts
51 photos

For my screw down regulators I make the seat part from a bearing grade PEEK. This gives a perfect seal and the valve never seizes shut when the boiler cools down. I find the control to be very gradual and smooth unlike some of the regulators on locos I've driven where it's all or nothing!

The thread on the one for my Helen Long uses a 3/8" BSW thread and for normal running the regulator is barely cracked open, no more than 1/8 of a turn. Any more than a 1/4 turn and the opening makes no difference as the steam flow is controlled by the valve gear rather than the regulator. The pointy bit has an angle of 120°.


I added the spring to take up any backlash in the thread but found it wasn't necessary.

And yes, the tube is brass but it will probably outlive me! Copper would have been a better choice.


David Wasson09/02/2018 21:05:18
146 forum posts
42 photos

Hi John,

Your regulator looks great! Yes, you are correct, I run with the regulator open about 1/8 of a turn, anymore than about 1/4 of a turn does nothing.

As for making the tube out of copper, I would be careful. When you close the valve tight, all the tension is on the tube and transferred to the three little flat head screws at each end. Copper is pretty soft and it might actually stretch at the screw holes. Given time, it might eventually break. Just a thought.


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