# Coal fired boiler - Aster design



## Pauli (Jan 3, 2008)

The design of this coal fired boiler intrigues me. Aster Europe / Twerenbold has designed it together with Aster Japan.
Follow the link, and click on the photos to enlarge;

http://www.astereuropa.com/index.php?option=com_content&task=view&id=51〈=en

I cannot se any stays. Neither to the sides of the firebox, or to the crown. I'm also speculating that the firebox top / "crown" is "simply" a semi-circular section of a tube. Think two circles / tubes. Now move the smaller, inner tube downwards, out "through" the bottom of the large tube. Then cut away the the overlapping bottoms. The cross-section would be something like a very exaggerated qarte moon-phase - but with the "tails" forming like 3/4 of a circle. Do I make sense???









Maybe I'm just missenterpreting the photos?! Maybee someone else has experience of similar boilers - perhaps also from Aster?

My speculating, is that perhaps the protruding bottom rectangular part, actually might provide enough "staying" stiffness by it self. Especially since my own experience from my Aster P8 / BR38, is that the boiler is made from very heavy gauge copper - something like 2,5mm (1/10"). 

I find this heravy gauge very clever, since this way the boiler material itself stores very much heat, and evens out teperature fluctuations from new cold water. In this case, it would also even out the heat generated from coal firing?!

In fact, on first viewing the photos, I thoght there might be no water in the backhead / around the fire / at all. That would mean relying on the heavy gauge copper transmitting the heat to the water in front - of course in conjunction with the smoke gases. However, I find this unlikely. Also the backhead fittings make me inclined to think more conservatively 

The very circular cross-section of this design also makes me think it is a very good candidate design for anyone wanting to convert a 1:32 to coal firing. What do you think?

Since I lack coal firing experience, can someone enlighten me on the ashbox design, please?
- The square hole in one shortend, is it supposed to be facing forward (toward the smokebox)? 
(I crept under a Polish small shunting engine the other week - it's standing outside a Harley Davidson shop in Stockholm! - there, air intake hatches could be opened both forwards and backwards.) Also, the semicircular "hump" inside, is it to accomondate a driving axle? Wouldn't that complicate emptying ashes??


----------



## AzRob (Sep 14, 2009)

Link isn't working for me...


----------



## Pauli (Jan 3, 2008)

http://www.astereuropa.com/index.ph...〈=en


----------



## David_DK (Oct 24, 2008)

Hej Anders 

Long time. since we have heard anything from you. 
I think the 140c boiler is speical since it is so small. But it would be nice to see a actual drawing. 
Are you planning to convert the Br38? 

Anyway Im going towards coal myself. You can follow my steps (going slow right now) at http://www.havebane.dk 
Look at "Project C62". 

Kind Regards 

David


----------



## Pauli (Jan 3, 2008)

Hello David,

I playing with the thought of using the boiler casing, driver's cab, wheels and tender from an electrical Märklin BR18 / S3/6. Thjey can be bought for something like 800 USD / 650 Euro. I would manufacture a new frame - and a coal fired boiler (maybe comission the boiler). And by the upgrade valve gear and cylinders that WYCO make for the same Märklin steam version. ( 850 Euro?) All in all, such a project could result in a budget coal fired big and beatiful engine!



I was pleased to read that you are satisfied with the WYCO uppgrade on yor site. (English version / translation of the account under way on Davids site.)


However, part of the reason for choosing the Märklin S3/6 (BR18) model, is that it has a very wide firebox and thus grate, wich allows for more coal beeing burned = more heat = steam, or longer time between shuffeling in new coal 


This very circular, and I would also agree - small coal boiler, allows for a wider choice of models = prototypes narrow fireboxes.In fact, this particular design would probably waste the advantage of beeing able to build a wide grate.


----------



## Dan Rowe (Mar 8, 2009)

The boiler construction can be seen fairly clearly in the photos. The side view shows that the pressure shell was was cut away for the firebox but a small tab was left and it was flattened and bent to form the upper edge of the firebox side. The rest of the firebox side sheet is a single piece forming both sides and the crown sheet. The side view also shows a small round sivler solder joint at the ends of the flat sections of the presure shell. I think these are riivet joints to hold the two sheets together for silver soldering. 

Because there are no visible staybolts I suspect that the arch of the crown sheet starts at the joint between the firebox side and the pressure sheel. This design is very similar to the design in "Steam Trains in Your Garden" by Brian Wilson. He used a flat crown sheet with 2 vertical staybolts but the dry side firebox is similar. With a narrow firebox dry side walls give more space for the grate and coal. 
Dan


----------



## Steve Shyvers (Jan 2, 2008)

Nice boiler design and very informative photos. I am curious about what the fitting is that is on the bottom of the boiler just forward of the firebox. It is not the feedwater clack, because that is on the backhead. Some Aster boilers had a blowdown valve at this location. Perhaps that is what it is. 

Steve


----------



## seadawg (Jan 2, 2008)

Thanks for sharing this discovery. I've got some boiler burner mods in my head and things like this add fuel to the fire.


----------



## JEFF RUNGE (Jan 2, 2008)

Do you think we could talk them into doing one for the USRA Mikados??


----------

