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Discussion Starter · #1 ·
So far many, many hours have gone into a 3 week period with high hopes of running at Cabin Fever. Well, the best laid plans almost made it happen... We look forward to the President Day's run at Steamtown in Scranton PA. All that remains to complete the Version One retrofits is the final pipe fitting and a test firing (or two).

Many aspects of the upgrades and changes were developed and shared by Gordon Watson:
Version 1-

Crosshead- pin and blind nut


Pin (top is redesign and bottom is OEM)


The pin with the new design to strengthen the crosshead: pin with backing plate





Steam pivot joint





Ryan and Jeff have made some changes to enhance performance


Cylinders- bored out ports along with the increase in size of the steam/exhaust lines help improve the steam delivery.


Dual throttles with in cab deadleg lubricator:
-The concept of dual throttles was to fine tune each engine and allow equal capacity to both engines.
-The in-cab lubricator feeds the front engine, there is a separate one for the rear engine
Thanks to Justin for his boiler work in setting up the second throttle.



Second deadleg lubricator



Suspension- extensive refinement to ensure all wheels are running true on the track along with the correction of the saddle/center pivot (side benefit allows the boiler to sit level).






Ease of access:
Relocating the bypass valve under the cab



Upgraded bearing inserted into the rods, along with lap joint pins silver soldered: replacement on top, OEM on bottom.
-Note: the replacement main driver bearing is missing for the replacements





Along with special effects:

Lights
Sound of air pumps



The next upgrades will be the combination levers, new slide valves and extention of the valve rod.




We will be posting logs about this process, eventually ending up in the in the information section here on MLS. Once the entire engine has been completed from mechanics to cosmetics the log will detail the changes from the standard AC-12
 

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Ryan - my sliding pipes have 2 o-rings. I suspect it is that way so that it wont leak. How does the single (one one each end) o-ring system hold up?
 

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Discussion Starter · #4 ·
John
The design works well as shown in the videos from Dr. Rivet and CF 09:



Cabin Fever 09 (latter portion of this video)
 

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I like the dual throttles. I have been contemplating incorperating that into my project, and i see you have already done it. Did the single throttle favor one unit over the other for power distributoin?

Tim
 

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Discussion Starter · #6 ·
Tim
The cab forward design had a limit valve allowing restriction of steam to rear engine (under smokestack). We decided that it would be better to have independent steam lines and controls per engine.
 

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The reason for the auxillary throttle was to keep the articulated engine from hogging all the steam when it slipped on oily track. My solution was to add a leaf spring at the pivot, and one at the slide plate so the articulated engine carries it's share of the boiler weight.

As far as the crosshead main pin being loose, I soft soldered it in place.
 

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Charles: Very nice set-up for the steam pivot. That's how it would have been done on the real thing, except they would have used a series of cast iron rings.

Great work: Bob
 

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Discussion Starter · #9 ·
Bob
Thanks but credit goes to Gordon on this scale replication. We simply copied his masterpiece (with his permission). Well, back down into the shop for a steam test of this Version 1 retrofitted Cab Forward. If all goes well we will post a video of it under steam this evening.
 

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Discussion Starter · #10 ·
First test run... despite a small steam leak in the joint due to missed a bit of solder the outcome met our expectations, video at bottom of post.


New oil line from the front lubricator to the cylinders:




Steam pivot, smokebox fitting. The"dogbone" connects from here to the other cup on the steam tee itself.




New larger steam exhaust lines





Video of test run:
 

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With two steam valves, when you turn them on, how do you know when both engines are pulling the same? To change speed you have to change both valves.
 

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Discussion Starter · #12 ·
Dan, et.al-

We had an opportunity to experiment with this particular locomotive. Kind of like double heading two engines for a train. It has a wow factor that is unique, but we do not foresee it being cost effective or practical for others to do.

Better, thinner wall 1/8” piping and attention to detail in making sure the bends and passages are obstruction free goes a long way in making sure the loco operates to the individual runner’s satisfaction.

This particular locomotive has had all of the pipe work replaced with new (including superheaters made from thin wall hypodermic tubing) and all ferrules and unions have been relieved to reduce restriction.

As we all know the Cab Forward has two independent engines. Despite efforts that should balance the performance of each engine so that the split of steam flow would be 50/50 to each engine, there is a difference in steam delivery runs along with requirements for each engine. The front engine with the axle pump and the long run of the steam line to this engine; Line runs through the boiler, out of the smokebox, and backtracks under the boiler shell about halfway.

Along with weight distribution (thus Dave H leaf springs, we plan on weight in smokebox) can be cause for differences in performance using a single throttle (i.e. breaking loose). The theory behind this is that having two throttles, the steam flow is properly distributed amongst both engines, without a bias from one engine or the other. In addition, each throttle has it’s own drypipe.

As to actual operations.....
In principle both throttles are identical so opening them the same number of revolutions on each knob should be approximately the same amount of steam for each engine. Monitoring of the speed is also indicated by sight and sound of each engine (worked well on the bench), much like when double heading locomotives. The rear engine (smokebox end) has a shorter run of pipe, so it will get steam a fraction quicker than the front, which has another 6” of pipework to traverse.

Yes, to change speeds one has to adjust both throttles, much like the OEM limiting valve by starving one engine(rear) to ensure the other(front-cab) running the axle pump got the necessary steam. Without a doubt the AC-12 with this setup could easily be started using one engine only then engage the other with a full train behind it if it is a question of coordinating between the two throttles. One could easily setup a different throttle knob design to tie the two together allowing both engines to be engaged in a single motion by the operator.

For most Cab Forward owners such aspects would not be a consideration, just put it on the rails and enjoy their wonderful AC-12 but we kinda like the "what if...." regarding performance.
 

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I guess the only way to see if your "improvements" have actually improved anything would be to have it pull on the drawbar pull at Diamondhead to see if it compares favorably with the ten plus pounds that Dave Hottmann's pulled.
 

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Bruce,


It would be great to see just what the results would be. The Dave Hottmann performance will be nearly impossible to beat, given the huge difference in drawbar pull between Paul Lator's sweet running AC-12 and Dave's!
Unfortunately, Diamondhead and Cabin Fever always seem to be the same weekend. Is there any chance you will have the drawbar pull device set up anywhere sooner than Diamondhead next January? NSS in Sacramento in July? ECLSTS in York in March? Plans are for this locomotive to be at both.

Or you could make the 12 hour drive to Scranton President's Day weekend!!!


In addition to performance improvement on this locomotive, the current switch from saturated to superheated steam had as an objective a decrease in burner noise. While the modified engine ran very well, the length of lines and increased saturated steam consumption really required a high burner setting. Here is a double header at Dr. Rivet's in June with the noisy burner subject engine in front and Paul Lator's mid train.

http://www.youtube.com/watch?v=J7e88e_yeE4

And another noisy runby preceded by John Allman's H6.

http://www.youtube.com/watch?v=ud9WxQPbJ6o

Hope all is warm in Easley, South Carolina. Glens Falls is hoping for a high of 19 degrees today!

Best regards,

Alan
 

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Discussion Starter · #15 ·
Alan
In the most recent video from last night we did not have the air flow adjusted thus a bit of howl....
 

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1/8" OD Hypodermic SS 304 tubing. This was had from Small Parts and was the most suitable tubing I could find that carried close to a 2mm inside diameter (matches the intake and exhaust ports on the cylinders) and was still easy to braze, cut and bend. Small parts considers it heavy wall tubing, although I have never tried any of their thin wall, fearing that it could burn through during the service life.

It can withstand plenty of heat and is a dramatic improvement over the oem tubing, which carried a ~1mm (a hair over 1/16") inside diameter.

Link to the tubing used:
ss 304 hypodermic tubing
 

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Alan,

First and most important - it's a gray dismal day of only 50 degrees today. Saturday it was sunny and in the 60's. Plenty warm to be out working on the layout. Trackwork has been started and we should be in operation shortly.

The July and March dates are already taken up by other committments and I've forgotten how to drive on snow and ice so February is doubtful, also a week following the February date I am in charge of the local train club show here in SC and have lots of last minute arrangements that I will need to coordinate. We are having a steamup area at this show for the first time and I could bring the drawbar pull equipment to that easily. Go to
[url]www.crmha.org[/url] for information. Why not come south where I can almost guarantee better weather than you'll be having!
You have noticed that Diamondhead is officially from Sunday to Saturday next year? You could steam for five days in Mississippi and then fly north to steam for two more in Pennsylvania!


The exhaust was the only thing I heard on Dave Hottmann's loco as it was trying to break my 20lb test line tied to its coupler. It was much quieter and smelled better than Bob Pope's diesel.

Thanks for the videos. Had to miss Dr. Rivit's steamups as I was preparing/recovering from heart surgery. If I get invited this year I hope its on a weekend I can make it. We have weddings and family committments every month from May to September - all of which are in the upper midwest.
 

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Discussion Starter · #19 ·
Here is a photo of the "back head" with the new arrangements of having two throttles. One might ask why the twisty pipe work on the lines....to allow easy removal of the jets:

The twist and turns from point A to point B for steam delivery were well done by Jeff in the cab, while Ryan was doing the job of soldering in the final stages of steam connection at both ends:

 

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Posted By Shay Gear Head on 01/26/2009 1:39 PM Alan,
 
First and most important - it's a gray dismal day of only 50 degrees today. Saturday it was sunny and in the 60's. Plenty warm to be out working on the layout. Trackwork has been started and we should be in operation shortly. The July and March dates are already taken up by other committments and I've forgotten how to drive on snow and ice so February is doubtful, also a week following the February date I am in charge of the local train club show here in SC and have lots of last minute arrangements that I will need to coordinate. We are having a steamup area at this show for the first time and I could bring the drawbar pull equipment to that easily. Go to [url]www.crmha.org[/url] for information. Why not come south where I can almost guarantee better weather than you'll be having!  
You have noticed that Diamondhead is officially from Sunday to Saturday next year? You could steam for five days in Mississippi and then fly north to steam for two more in Pennsylvania!

 
The exhaust was the only thing I heard on Dave Hottmann's loco as it was trying to break my 20lb test line tied to its coupler.  It was much quieter and smelled better than Bob Pope's diesel.
 
Thanks for the videos. Had to miss Dr. Rivit's steamups as I was preparing/recovering from heart surgery. If I get invited this year I hope its on a weekend I can make it. We have weddings and family committments every month from May to September - all of which are in the upper midwest.

Bruce, The P-2 diesel was loud and smoked enough to put an Alco to shame.  But it did pull 10 lbs, 9.8 oz - more than 50% efficiency.  Last year my 16 pound P-1 pulled a little over 6 pounds and Charlie Mynheir said I had some work to do since his 0-10-0 pulled half it's weight. So I'm happy the P-2 could meet Charlie's challenge.  To do it, I had to change the gearing, put on a single-chamber tuned pipe (instead of the quieter double-chamber tuned pipe), and put on a new servo arm with greater throw.  Basically I undid everything that made it quiet and civil. So with the pull behind me, now my efforts are to make the diesel quiet and unobtrusive.  After watching the video, I never want it to be that loud or stinky again! Regards, Bob
 
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