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

LBSC 3.5" "Maisie" - steam regulator valve assembly

All Topics | Latest Posts

Search for:  in Thread Title in  
bogus29/05/2020 21:19:20
31 forum posts
54 photos


i'm struggling trying to figure out how regulator valve assembly is made and how to take it apart. I'ts kind of slide gate valve as i can see in the steam dome. But i do not know how to diassemble it. There is some backlash in the linkage which connects long stainless steel rod going from the handle in the cabin with sliding element that open steam channel. Pls, see the photos - regulator closed:


Regulator opened:


It looks clean as it is after soda blasting. However i'd love to have better response on regulator by eliminating the play in the linking elements.

From the smokebox it looks like this:


I'm affraid steam outlet is fixed to the boiler body for good:/ These three small threaded holes are for superheater assembly:


And this is how it looks like from the cabin side:


Unfortunatelly i have no book and it is hard to guess. I don't want to use too much force.

Can anyone chack in the book what is the design arrangment? The basic question: is the regulator designed to be repairable? 

Edited By bogus on 29/05/2020 21:25:36

Redsetter29/05/2020 21:33:08
153 forum posts

Just buy LBSC'S book on Maisie. Plenty of secondhand copies around, and I think it has been reprinted by TEE.

bogus29/05/2020 22:07:33
31 forum posts
54 photos

it's on my list

Phil H102/06/2020 08:57:14
357 forum posts
40 photos


I've just checked my LBSC Betty regulator drawing and I sorry to say that it doesn't help. It looks completely different.

Phil H

Redsetter02/06/2020 09:49:07
153 forum posts

From the photos it looks as if the regulator is working. Why the overwhelming urge to take everything to pieces?

If it ain't broke, don't fix it.

Manofkent02/06/2020 10:26:15
136 forum posts
29 photos


There should be two screws on the top of the boiler - 5 BA countersink if I recall correctly, that hold the regulator vakve body in place. If you undo these you might be able to move the regulator body sufficiently to see what is going on.


MichaelR02/06/2020 10:32:42
417 forum posts
81 photos

It's many years since I made my Masie but from memory. To remove the regulator rod take the regulator handle off, and unscrew the bush that the rod goes through and you can then draw the rod with the bush out, the rod has a stop collar behind the bush and a square section on the rod at the regulator valve end, the linkage at the valve can then be removed.


bogus02/06/2020 10:42:52
31 forum posts
54 photos

Thank you guys.

On mine there is only one screw - i suppouse this is the one (steel, round head, slotted):


I tried to move it but at some point of force i decided not to go any further. Maybe i'll try to heat it up. Maybe the builder used some kind of blue to seal it. However i don't understand how the rest of the assembly. Even if i remove the srew holding the valve body in place what about the other two elements:

1. the stem/bar(?) going to the handle in the cabin - here i assume it's only going via some kind of sealing. But here again: i tried to undo the threaded elements and give up at some point

2. the arrangement going from the valve to the smokebox. It is mystery for me... I thiught it should be rigid. I can't see any means to undo at the smokebox side:


The reason is two fold - i'm VERY curious and there is a backlash in the connecting linkage elements of the regulator valve. I can do ca. 15 deg of movement on the handle before the valve sliding plate starts to move in the opposite direction. For me it's way to much in terms of "response".

bogus02/06/2020 10:47:26
31 forum posts
54 photos

Any one can share some drawing of this arrangement please? Of course i can not be 100% that the builder of my loco have done it as per drawings. Howeve i studied many photos of other 3.5" gauge Maisies on the web and most of them have regulator arrangement in the cabin looking like on mine. Haven't seen regulator valve under the steam dome, though. Any one have photos of it? I couldn't find them on internet.

John Baguley02/06/2020 11:22:41
483 forum posts
51 photos

Hi Bogus,

Here's the drawing of the regulator arrangement:

maisie regulator drawing.jpg

To remove it you will have to first unscrew the fitting on the front tubeplate. It threads into the tubeplate and onto the end of the steampipe at the same time so will not be easy. You will either have to try and grip the outside with something or maybe put a couple of screws into the threaded holes that hold the superheater on and try unscewing it with a bar.

The steampipe may come out with the fitting. If not, you will have to remove it by unscrewing it from the regulator block. One way is to tap the square end of a file shank into the end of the pipe or a square file and use that to unscrew it. You will probably damage the pipe trying to get it out!

Once the steampipe is removed you should be able to remove the regulator block through the dome bush after removing the screw on the top of the boiler that holds it.

Hope that helps,


bogus02/06/2020 12:23:01
31 forum posts
54 photos

This is the one i have! I reconize it THANK YOU John yessmiley Very smart arrangement. I guess i'll have to use HEAT during the job. These threads probably haven't beed touched since ages. And i bet someone used glue (or different type of sealing agent) to seal the things.

julian atkins02/06/2020 13:44:37
1238 forum posts
353 photos

Hello Bogus,

If you only need to deal with slack in the linkage of the regulator valve to the square on the regulator rod, then I would leave the regulator body and the steam pipe and tubeplate flange well alone.

You can remove the regulator rod and valve and linkage by removing the regulator handle and the gland for the packing. The regulator rod cannot be withdrawn at this stage because of the collar fixed to it as shown in John's drawing. Therefore you need to remove the flange that screws into the backhead bush.

Be very careful here if the backhead bush is screwed into the backhead as per the drawing (and not additionally silver soldered. Even if this is caulked with 'soft solder' the soft solder can shear.

You can then withdraw the regulator rod but before you do so put some wire around the linkage to stop the regulator valve and linkage falling into the boiler.

The wire can then be used to drop the valve down and be lifted out with the linkage and arm attached.



bogus02/06/2020 19:35:14
31 forum posts
54 photos

Thank you so much guys for your advices. It looks it will be an awkard job.

If i remember right the play is mainly (if not only) on the linkage that is connected to the valve slider block (light blue color in the photo). It looks like the holes the red screws are going through are worn. Julian if i understand you correctly - should i assume that if i undo the gland (bard blue) and flange (violet color) and slide the rod assy. out of the boiler the square section on the end of the rod will just slide out of the green element? Good point to suspend the slider first! Any way if i have to make light blue element i will still need to undo the red screws so i guess - remove the valve from the boiler. The thread numbered "2" should have more gripping force than the one marked "1" so "1" should give up first though there might be surprices (like glue). I'm not very into the imperial threads: thread marked "1" says 5/16" - but what pitch? All three marked "1", "2", "3" should have tha same pitch.

steam regulator valve arrangment2.jpg



julian atkins03/06/2020 01:58:36
1238 forum posts
353 photos

Yes, the regulator rod should slide out of the green bit on it's square.

You don't have to undo the red screws at this stage.The valve and linkage will drop down and be retrieved by the wire I specified you must add to stop these bits falling down into the boiler.

Don't remove your '1' and '2'. Don't disturb this assembly please!



bogus03/06/2020 10:28:13
31 forum posts
54 photos

Julian, you're totally right. I won't

Now i fully understand this part. Thank you. Double happy as i got message from my wife about delivery - i was lucky to find 5mm O.D. borosilicate glass capilary tubes, 0.8mm wall thickness so the capilary action false readings will be minimised. Rated for 26 bar of pressure. I broke water gauge accidentially during disassembly. What a day


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

Support Our Partners
Eccentric July 5 2018
JD Metals
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