# Cab Forward Ceramic Burner



## bille1906 (May 2, 2009)

After my successful conversion of the GS-5 from poker burner to ceramic burner, I decided to take on a real challenge. The Cab Forward.
This is a much more difficult job as the disassembly and assembly are more difficult and there is very little room for a firebox.
I started by disassembling the engine with help from the TRS website. The link to their thread didn't work but Googling it with MLS brought me to it.

Once I had the boiler off, I could measure and plan for the new boiler. The boiler cover is red, the boiler and new firebox are blue and the ceramic burner box is dark green.










The main surprise was the axle pump which was sticking out way above the drivers. I thought of moving it to the rear engine but the frame is different and it would involve shoe horning a new pump and bracket.









So, I decided to redo the existing one. I needed to get rid of the banjo fitting and cut the body down as much as possible. I start by trimming 1/8" off the body









I then replace the banjo bolt with a cap that will allow for just 1/8 of the ball diameter lift or .020" and drill out for a side mounted fitting.













































And here it is snuggled in place









There were a lot of tubes which were routed through the dummy ash pan which is where by firebox and burner go. TRS had installed some wonderful adjustable lubricators which I wanted to keep so this and the factory lines had to be on the same level as the frame. They couldn't go over it as the boiler is now there and not below it as the pilot truck is there.


















Now that I have a home for the boiler, it is time to get to the fun part. When you see this next photo, it may remind you of the comedian Gallagher or just something ugly, but sometimes you have to be daring like hacking up the boiler on an $8.000 engine









I set the rip fence to exactly 1/2 the boiler diameter


















The original backhead could not be removed in one piece because the heat needed to get the solver solder melted in all locations could be enough to melt the boiler shell. Once it is cut and opened up, the heat can be directed to the pieced to be removed.


















I rip a 4x4 piece to the boiles shell id. which is the width i want my firebox to be and with a compass draw the rounded top and then cut it on the band saw and clean it up on the belt sander.


















I mark the center of the former block, line it up with the center line of the boiler, clamp it in place and then hammer the sides in with a rubber dead blow hammer.


















I now lay the boiler on my scale drawing just to double check the amount to be cut from the sides.









Then on the table saw, I remove .200" 









I am now ready to make my new boiler parts.


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## scubaroo (Mar 19, 2009)

WOW!!
This should be an interesting thread.
Looking forward to more of your great work Bill!


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## bille1906 (May 2, 2009)

Yes, it will be interesting. since I have the boiler apart, I can replace the 3 mm main steam line with a 5/32" one which will more than double the flow through that tube. I am also going to fool around with maybe adjustable boiler mounts so the weight over the articulated chassis can be increased.


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## Kovacjr (Jan 2, 2008)

Very cool Bill. Always wished there was a locomotive type boiler on these big locos. Going to run really well. Are you able to leave it at just 2 large flues?


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## bille1906 (May 2, 2009)

Jason
I think the two large flues will work fine as they did on the GS-5

My ceramic burner design doesn't seem to be that critical on flue size and number.
The majority of the heating comes from the radiant heat on the crown sheet and I don't have any draft concerns.
With the 6" crown sheet, it should produce more steam than it will ever need.

If all goes well, maybe we can put together a train of 100 cars at Sac to see if it will match the Aster Big Boy
Wait a minute...I am getting ahead of myself, first I have to make sure it runs.


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## Tomahawk & Western RR (Sep 22, 2015)

this may be a dumb question, but ceramic burners use butane too, correct?
-nate


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## Tomahawk & Western RR (Sep 22, 2015)

also, if you were to remove the ceramic plate and put in a fire grate could you burn coal?


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## bille1906 (May 2, 2009)

Yes the ceramic burners use butane
Not sure there is enough vertical height to burn coal here. Also, it would be cumbersome to shovel with the cab Forward configuration.
Other than that, the locomotive style boiler works for coal. I use a dry firebox for my ceramic burners as it allows for a larger crown sheet. I have done both dry and wet and the dry actually out performs the wet, whereas it would be the opposite for coal. Dry fireboxes have been used for coal but the legs and backhead in the firebox area need to be secured with screws or rivets as the heat from the coal could melt the silver solder in a dry box.
As I complete the burner, you will see just haw everything works


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## Charles (Jan 2, 2008)

Tomahawk & Western RR said:


> also, if you were to remove the ceramic plate and put in a fire grate could you burn coal?


Nate
The SP Cab Forwards were oil fired thus never would have used coal. 

We are presently converting several Cab Forwards to AC-9 Yellowstone (best denoted by cab in the rear an GS4 style skyline casing along with cab and pilot type characteristics). Two of the conversions will be coal/alcohol.

Bill's option for fuel/burner setup an AC-9 would be a very appropriate.


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## Tomahawk & Western RR (Sep 22, 2015)

now a real coal fire cab forward would be fun to see
fireman has to go run down the running board, climb down steps, shovel a scoop of coal, run back to the cab... all while the engine is going at 50 mph....
charles did you get my PM?


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## bille1906 (May 2, 2009)

OK
While I was imagining the guy running along the running board, I decided to post some more photos.

Here is the old main steam line next to the new one. The old one id actually flared out a little on the end and is smaller 2 mm inside









Here is the throttle and the new steam line. The valve on the right is the limiter for the articulating chassis









The hardest thing to solder is the crown sheet in the firebox. Laying down snippets of solder and ringing the stays helps. the parts are also held in place with SS screws and copper rivets









I make up some nuts and ferrules for the steam lines i will need in the cab.









The boiler is pickled and cleaned up









The burner box needs to be square so I set it up using a scrap square piece and then solder the sides together.









Then I solder the two bottom pieces on in separate operations









And then solder the sloped transition piece. The box needs to be air tight and very strong to protect the fragile ceramic plate so I silver solder it together.









I tested it on the bench and it was only burning in the front of the burner so i added these two stand-offs at the end of the tubes.









And now a successful even burn









And one final test in the boiler









And a new over coat to keep it warm.


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## Skeeterweazel (Feb 11, 2014)

Thx for taking us along on this project.


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## Alan in Adirondacks (Jan 2, 2008)

Hi Bill,

An amazing build. Thanks for sharing!

Best regards,

Alan


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## StackTalk (May 16, 2014)

Skeeterweazel said:


> Thx for taking us along on this project.


Bill, same goes for me. I can't contribute anything on this topic but I am learning from and enjoying each one of your threads.

~Joe


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## richg (Oct 22, 2011)

Bill,Thanks for sharing your knowledge and skill with all of us and taking the time to post all the great pictures and explanations. Wish I had the skill and guts to cut up a engine like you do and have run better than before. looking forward to more.Richard


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## boilingwater (Jan 27, 2010)

Bill,
Good stuff as always. 

Regarding the burner design, how did you determine the "optimal" distance to the top of the crown sheet? Speaking of the Aster Big Boy, I have missing stainless plates in my engine used to prevent gas flow and burning under the engine. I wonder if a redesign using a ceramic burner might be a different solution to the problem....not saying better with the 3 tube flamethrower in there already but I'm curious to try your solution.

By the way, i wish I was one of your friends!!

Sam


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## bille1906 (May 2, 2009)

Thanks Sam
The minimum distance from the top of the burner plate and the crown sheet is 1/2". Anything over that is fine.
Without seeing the Big Boy, I would think a ceramic burner would work great. It has a 7" firebox which should provide plenty of heating surface. I would remove the SS arches as you want the radiant heat from the ceramic plate to go directly on the crown sheet.
if you use my style of burner, you will have to unseal the smokebox by opening up the bottom and remove the blast pipe nozzles.


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## boilingwater (Jan 27, 2010)

Bill,

Thanks. Please help me understand why the blast nozzles need to be removed with your solution.

I want to keep coal firing a potential option..

Best,

Sam


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## xo18thfa (Jan 2, 2008)

Hi Bill. Great work!. Had to laugh a bit. Table saw for a soldering bench. I thought I was the only one doing that.

I've asked before, but where do you get the ceramic material.

Take care, Bob


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## bille1906 (May 2, 2009)

Well
I worked on assembly today, Not an easy task on this baby

The boiler fits snugly in the boiler casing and that is supported by a saddle in the front (or rear in the cab forward) and is attached with two small screws which are accessed through the center of the case. I guess there is a lot of strain on this area as the threads in the brass saddle were stripped out. I drilled and tapped the holes out to 8-32 which hopefully will prevent this from happening. The rear of the boiler case is supported by two screws in the side of the dummy firebox.
Because of my real firebox, I needed to do some fabrication.
The bracket is two-piece. I start by scribing out the clearance I need for the jets.









I cut it out and because there is a thin cross section, I reinforce it with a 1/8" square bar. I soft solder it as not to anneal the structure. I then cut the upper piece to overlap it









Here they are mated together









Now I do several things. I had to remove the rear floor bracket for firebox clearance so I will add two tabs to this bracket for that purpose and at the same time, I overlap the thin area on the left to strengthen it. I also want to raise it 1/8" so you can see the old holes above the bolts.









The superheaters are 3 mm which is stretching it but one had such a sharp bend in it that it was partially kinked. I rounded it somewhat by squeezing it in the vise but it still was restricted as in the photo. As I had to modify the other end anyway, I decided to make a new on with smoother bends and out of 1/8" which is a little bigger


















Here is the new backhead or is it the fronthead. To tell you the truth, in all the excitement, I lost track myself.


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## bille1906 (May 2, 2009)

Well, the redo was a success but not without incidents.

My first test was with just the engine on my 9-1/2' radius oval track. After clearing the water from it it started gaining speed heading into the curve where it slowed down and finally derailed.
Upon inspection, I could see that the drive axles did not have enough lateral movement and were binding up and finally climbing the rails. I tried it on a 10' section with the same result.

Then I knew I had to do some major changes.

I had this board which I had made up fot the Triplex which supports the engine on its back without letting it roll over.









I then measured the lateral play in each wheel set. As you can see, It varied from .002 to .074









I then checked the gauge by measuring the distance between the wheels and it was consistent throughout, within a couple of thousands 
I then removed the wheels and checked the wheel hub thickness and that is where the problem was.


















I set the wheels up on the lathe to turn down the hubs when I noticed there were shims on the axle of .019 or 1/2 mm which were bonded to the hub. An exacto knife pried them away where I could cut them off with a pair of Dikes, thus making the fix easier than I had anticipated, I left the two front axles alone as there wasn't enough clearance between it and the crosshead guides to spread it out.
now that the wheel movement was such to accommodate a 9'-10' track, I had to make sure the side rods had similar play. The wheels have a stud with a shoulder which sets the side rod play. The side rod is 3 mm thick (.118") so the shoulder needs to be at least that deep. Again, I found variances from .135" to .070". It seems like the factory made the screws that hold them on bottom out to make up for this variance, and a couple of the screws had a threadloc on them.
I brought all axles except the front ones to .135" with the spacers below and left the front ones with the bottomed out screws to keep the same clearance there.
This photo shows the difference between two studs.









Here are the spacers


















The engine now runs smoothly around the entire track.
The ceramic burner provides more steam than it needs and it runs at a low gas setting at prototypical speeds pulling my drag car which is a one pound draw bar pull (about 15 -20 freight cars)


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## Tomahawk & Western RR (Sep 22, 2015)

all i can say is WOW!

this may be a dumb question, but,:

1. why 2 pressure gauges?
2. where is the johnsonbar/reverser in the cab?


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## bille1906 (May 2, 2009)

The only dumb question is the one you don't ask
Thanks for asking
It was already that way. Not sure if it is factory or add-on
It is so you can see the pressure from either side.
This has a screw reverser it is the rod sticking up in the front middle of the floor with the slot in it.


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## Alan in Adirondacks (Jan 2, 2008)

Hi Bill,

I agree with your lateral play assessment. When doing the AC-6 "flat face" project, the drivers were all changed to spoked F-4 2-10-2 drivers that had thinner hubs and therefore the necessary lateral play like you discovered. It worked like a charm!

The other thing with cab forwards is that I always lube the axles by putting oil between the back of the driver hub and the axle box. That way the face of the driver hub doesn't dry out and slow it down on the curves.

Thank you for the great write-up on the ceramic burner.

Best regards,

Alan


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## lkydvl (Jan 2, 2008)

that was an incredible bunch of work. Thank you!


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## bille1906 (May 2, 2009)

Sam and Bob
I was just reviewing the build and noticed I didn't answer your Questions
Bob I think this link will take you to the downloadable catalog. the plates are on page 47
http://www.pollymodelengineering.co.uk/sections/bruce-engineering/price-list.asp

Sam
A coal boiler needs a draft to burn which means the smokebox must be sealed and there needs to be an air source in the firebox (the slots in the grate). The nozzle(s) at the end of the exhaust pipe create a low pressure in the smokebox through the venturi effect which draws the air flow through the coal burn and out the stack.

The balanced ceramic design that I use needs to have equal pressure in the smokebox and firebox (excluding the gas pressure) In my design, the firebox is sealed and the pressure of the butane and air drawn in at the jet holder along with the heat wanting to rise, cause the flow out to the unsealed smokebox and up the stack. 
Removing the nozzle doesn't get rid of all of the drafting but that along with opening up the bottom of the smoke box does the trick. 
If you were to do a sealed firebox as I have done here, there would be a noticeable loss of heat under steam. 

You could go with a drafted ceramic burner which they use in the UK with success on smaller engines but the performance is less as it is drawing cold air into the firebox ( I have tried both systems). But, I think that because of the large firebox on the Big Boy, You could do it. You would use a smaller plate with air holes on the side or a hole in the center of the plate going all of the way through the plate and box.


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## HMeinhold (Jan 2, 2008)

It is actually quite simple: In order to get maximal heat output the ratio of air and combustible material must be balanced. Too little air and the fuel does not burn completely, too much cools down the hot gases. In a gas burner (poker or ceramic) the kinetic energy of the pressurized gas is used to draw the correct amount of air via the mixing tube (with e.g. a sleeve to adjust the hole opening). The smokebox needs only keep the exhaust pressure low enough (e.g. slot in the bottom) so the burned gas can get out. In a coal or alcohol fire the air must be drawn from the outside and the easiest way to do this in a loco is to create a partial vacuum in the smokebox. The amount of air can be controlled with dampers. In all three cases the air/fuel mixture needs to be as homogeneous as possible, which is a different story and needs some ingenuity with baffles etc.
Regards


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## joanlluch (May 20, 2017)

Hi Bill,

I have read with interest all your work and posts in this forums. I am new to this forums but not to model engineering. I am currently building my own-designed pacific locomotive on 5" gauge and I plan to fire it with butane gas. I regard your work as pretty remarkable!.

I wonder if you could clarify for me a couple of aspects of your style of burner, as I believe yours is the right approach to gas firing. Although my loco scale will be bigger, I am mostly interested in learning and I am sure I will be able to learn from you.

My questions are rather simple, as I believe that I understand the most basic concepts. I will quote you below and then ask my questions if you don't mind to reply to them. I would really appreciate that.



bille1906 said:


> The locomotive style boiler works for coal. I use a dry firebox for my ceramic burners as it allows for a larger crown sheet. I have done both dry and wet and the dry actually out performs the wet, whereas it would be the opposite for coal.





bille1906 said:


> The balanced ceramic design that I use needs to have equal pressure in the smokebox and firebox (excluding the gas pressure) In my design, the firebox is sealed and the pressure of the butane and air drawn in at the jet holder along with the heat wanting to rise, cause the flow out to the unsealed smokebox and up the stack.
> Removing the nozzle doesn't get rid of all of the drafting but that along with opening up the bottom of the smoke box does the trick.


Question 1: Why do you think that dry firebox does outperform the wet one?. Is it just a matter of potentially more heating area on the dry firebox crown compared with the wet one, or there may be a different reason?

Question 2: I fully understand the concept of your balanced pressure design, but I struggle to visualise the way to "opening up the bottom of the smokebox". How did you do that?, I can imagine a circular opening on the bottom of the smokebox, similar in diameter to the chimney, at the same vertical axis, but I really do not know. Please can you clarify it for me?. Sorry if this was already posted before, but I do not seem to find it. 

Thanks for any help.


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## bille1906 (May 2, 2009)

By going with a dry firebox, not only do you get a larger crown sheet but you also have more room for tubes thus more heating surface. As the ceramic burner produces more radiant heat than conductive, the wet sides don't really help that much.

A hole in the bottom of the smokebox where the exhaust tube comes up which is at least as big as the stack diameter is necessary.

For your scale, you may need more that the two jets I use. Test the burner box mounted in a vice before installing to make sure the entire ceramic plate burns bright.

Let me know if you need any more info


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## joanlluch (May 20, 2017)

bille1906 said:


> Let me know if you need any more info


Hi Bill,

Thank you very much for your reply. That was pretty informative and useful. I have yet another question that maybe you can clarify for me.

I looked at ceramic burners for the size of my loco (such as 170 x 220 mm or similar) and found that the more powerful ones are rated at a maximum of 5.5 Kw heat power. This seems very towards the lower end for the needs of a big 5" loco -specially if we plan to use it for heavy work and load- at least when comparing with similarly coal-powered locos. I suspect that the overall efficiency of the gas fired loco with ceramic burner will outperform an equivalent coal based one, taking into account the lack of back pressure at the cylinders and the possibly better efficiency of the boiler. Any thoughts?

Thanks again in advance


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## bille1906 (May 2, 2009)

Can you post a link for the burner you are contemplating
Thanks


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## joanlluch (May 20, 2017)

bille1906 said:


> Can you post a link for the burner you are contemplating
> Thanks


Hi Bill,

I am apparently not allowed to post links yet (not even as text) because I am too new in the forums, but I suppose you should be able to search them based on the instructions below, (Sorry for that, I'm frustrated too because of this restriction on the forums)

So, 

1 - One possibility is the "NP burners" from Polidoro

This is not a radiant type but it can deliver almost 25kW for the size I am considering (158 x 153 mm). This is just above the required power for the loco running continuously at full speed and full load. (Not that the loco will possibly ever work that hard, but it's a reference figure for design purposes nonetheless). My understanding is that the air tight firebox concept is not possible with this kind of burner.

2 - Another possibility for true radiant effect is the "Emitter Burners" from Micron Fiber-Tech

These ones are slightly bigger in size but rated at 6-8kW, which may be enough for normal (realistic) operation of the locomotive, but not powerful enough if we take into account the locomotive design figures based on the computed steam consumption at continuous operation at top speed.

3 - Actual ceramic burner

If we go to actual "ceramic" burners, then the power gets even lower, at about 2.5kW or 3kW depending on the particular manufacturer.

[I do not want to spoil your thread with possibly unrelated stuff, maybe should I start a new one for asking my questions?] 

Thanks


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## HMeinhold (Jan 2, 2008)

A friend of mine built a ceramic burner of about 4"(?) diameter for a vertical boiler and his output is >10kW.


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## joanlluch (May 20, 2017)

HMeinhold said:


> A friend of mine built a ceramic burner of about 4"(?) diameter for a vertical boiler and his output is >10kW.


Yes, that's totally possible, but in such case the burner tends to produce a flame above the ceramic surface thus reducing the radiant effect and working more like an atmospheric burner provided there's enough air. I mean, a ceramic burner operated above its rated power will no longer work properly (or as designed), specially by loosing some (or most) of its radiant effect.


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## bille1906 (May 2, 2009)

joanlluch
Did you get the personal message I sent you ?


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## joanlluch (May 20, 2017)

bille1906 said:


> joanlluch
> Did you get the personal message I sent you ?


Hi Bill,

No. I didn't get it. I am not sure why. I only have a welcome message from an administrator in my Private Messages Inbox. Or is there anywhere else that I need to check?

Thanks


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## bille1906 (May 2, 2009)

At the top of the page under the search bar there should be a welcome joanlluch and below there should be notifications and a number. click on that and it will list the personal message notifications
Let me know if you don't have it and I will post the message here.


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## joanlluch (May 20, 2017)

bille1906 said:


> At the top of the page under the search bar there should be a welcome joanlluch and below there should be notifications and a number. click on that and it will list the personal message notifications
> Let me know if you don't have it and I will post the message here.


Hi Bill, Yes that's what I referred to. I only have one message there and it's the welcome message that I got the day I joined the forums. I do not have any more messages than that !!

I have sent a private Test Message to you, and it has apparently went through. However, I insist. I have NO message from you. I am sure something went wrong when you sent your message.


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