# Cab Forward review (graphically intensive)



## rbednarik (Jan 2, 2008)

Those of you who know me know that I'll tear an engine down and build it back up again before it even gets track time.  Today I took some time and began with some basic disassembly/notes on the AC-11/12.  First thing first, had to finish my instructions on how to install the pilot and trailing trucks.  Need a copy?  Give me a shout off list (email).  *Clarification:*
Please note: this thread is designed towards to making an assembly (disassembly) “manual” for those who wish to explore or, should the need arise, fix their SP Cab Forward.
I highly endorse the AC-11/12 as a quality and good base line performing engine based on previews at Diamondhead and Dr. Rivet’s meet.  Those who desire to know how it is made and others that would like to know the perform characteristics we hope to offer some insights.

* **56k turn away, unless you have three days to spare to view the pics!***

After I got that done I turned to correcting one of the problems with the engine we got in yesterday.  The radius arm was being fouled on a piece of detail piping when the engine was being to be put into full forward (what would be reverse in real life):









A quick bit of fiddling with a pair of no-mar pliers did the trick, apparently the pipe had come disloged in transit.   The engine now ran equally well in forward and reverse (air test).  

Since it's here for R&D work, I decided to look at the revised feed pump system more in detail.  Yesterday I quickly took apart the bottom banjo fitting to see if the pump was revised or not.  Survey says:  YES!









With that revision crossed off the master list (many thanks to Accucraft for listening to my feedback!), I had to look at the backhead check valve to see if they completed the puzzle.  In order to do this properly, I had to remove the cab.  While it may look like a daunting task, it's rather simple.  4 screws on the base of the cab straddling the doors and three on the back wall.  Remove the grabrails on the side steps and gently wiggle the cab free.  Here's the convertible style CF, great for the bay area sun!

















In the previous photo, I had already removed the lubricator to allow me to examine it closer:









Now I could get at the check valve, which is in two parts.  The bypass valve doubles as the seat for the SS ball (yep, they got it right!) while the valve body has a proper ball and lift limiter.  It's baiscally a mirror image of what I have been doing over the past 6 months on GS-4's, as told* here*.  

Some pics for your viewing enjoyment:

















Even without a proper steam test, I can be rest assured that this water feed system will work 99.9% of the time.  Also, having the ball valve'd pump and check valves means that the resistance of putting water in is less than 3psi.  See my GS-4 article (link up above) for info on this.  

Now, there were a few more suprises that I wanted to share with all of you.  First is the top of the boiler.  Even though I am a little upset over choosing form over function in regards to eliminating the two safeties mid-boiler (opting instead for a prototypical turret on the midsection and relocating a safety to the cab), I must say, the ease of which the faux turret is removed to service the safety is a great item to have.  Here's a step by step (Pics are self explanitory):

































Just behind (Cab forward, remember?) the safety valve turret is the steam dome.  Suprise suprise, this one actually is functioning (we need a hand clap smiley!).  Unscrewing the M2 hex screw shows this:








Unscrewing the steam dome, which can act as a filler/drain plug if necesary, shows the drypipe:









*I had to get a pair of thin nose (read: needle nose) pliers and pull the dry pipe up on this particular engine, as it was hanging down in what would be water space.  Quite easy really, and a quick tug kept it in place (annealed copper, very soft)*

Finally, I wanted to know just how easy it would be to get the running boards off of this engine.  Removing the decorative cover (3x 1.6mm screws) revealed a familiar sight.  It uses brackets and 1.6mm phillips head CS screws. Just a simple matter of knowing which screws to remove.  

















That's all for today, but I can leave with this....I'm going to need to make a new work bench to be able to get the whole thing up there!









I'll cover the tender ins and outs tomorrow.


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## Jerry Barnes (Jan 2, 2008)

Nice work Ryan. Not sure how you can do anything with such a neat workbench though! I have not seen the top of mine in weeks. Sigh....maybe you'll inspire me to clean up? NAH!  
Jerry


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## rbednarik (Jan 2, 2008)

Jerry, 
That took about 5 New Years resolutions to tell myself to keep it clean. It helps when I have a big bin I throw my jewelers tools into and place that up on a shelf to my right. I'm looking at replacing the top of the bench this spring, white board works well and cleans easy (not to mention cheap! 4x8 sheet costs less than $10), but scratch it and your left with nice compressed fiber brown spots! 

Remember: 
It's only a mess if you think it is! Disorganization is organization, etc


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## Charles (Jan 2, 2008)

Most of life's treasures are brought about via organized chaos....all those wonderful crazy moments, surprises and unexpected things turning up that no matter how well prepared or organized you got to go with the flow. 

Ryan 
Many good concepts from your brief that can upgrade the AC-11/12 to optimal performance.


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## Shaylover (Jan 2, 2008)

A quick question to one of the lucky owner's of an AC-11/12.   Do the cylinder cock levers foul the railhead when in the open position?


This was one thing that spoiled the NGG16 as far as I was concerned.  I still have to find a way of fixing this little problem.


                         John de VK2XGJ


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## rbednarik (Jan 2, 2008)

John, 

Not necessarily solved, but the levers have been shortened to be above the height of the railhead. 

To everyone else: 
Photos this weekend of the engine and tender all to bits (well, close at least!) Watch this post around dinnertime (EST). Working on making disassembly/reassembly manuals...but that's going to be a while.


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## rbednarik (Jan 2, 2008)

Now on to the half of the engine that is often overlooked:

The tender is not difficult to disassemble, although a little involved.  Here you see the inner tank and outer decorative shell, which seems standard for the 1:32 line from Accucraft, excepting a few engines with Vanderbilt tenders:









It seems that the engineers at Accucraft did not give much forethought to being able to separate the tender shell, as it involves removing the front footplate on the tender.  Seems simple enough, until you realize that the ladder is spot soldered on over three critical bolts that hold the deck on, one rung placed so that two of the bolts are quite inaccessible.  Some careful maneuvering to remove the ladder and squeeze the 1.6mm nut driver (which I had to taper the end of in my lathe so that it wouldn't foul up on the rungs) in and the front plate was free.  I should note that it could be possible to remove all the feedwater piping and gas pipe before doing this, but it may not make it any easier to remove the main shell.  

With that out of the way, we can see the enormous size of the gas tank on this brute:









To me, it looks as if it is a 2 cylinder shay boiler soldered up, but don't quote me on that.  The handpump is their standard large bore pump that is better suited for a Ga. 3 model, in my opinion.  With the changes made to the axle pump and new/revised check valve (see original post), the pump action should be significantly less tiring on the operator.




The water bath for the fuel tank and the feed-water tank are one in the same, which makes for easy filling and draining.  Speaking of draining, a new feature implemented on this engine is the floor drain for the water tank.  A very novel idea which works quite superbly compared to getting the 5-fingered crane out and inverting the tender.  A bit unsightly on the right-hand side of the tender though a touch of paint would work wonders:







 

*I should note that it is quite hard on the fingers to open, but some oil and use should help the screw loosen up.  

The tender connections are still the same bulky fittings that were used on the GS-4, S-12 and K-28.  I plan on adding quick disconnects this week, and will post a brief how-to for those interested.  I imagine the install should be similar to the *GS-4*. 









One of the items that was suggested to Cliff after seeing and "test-driving" the prototype was that the bypass return line be extended so that it could be seen from the rear hatch opening in the tender.  Unfortunately, the pipe was left where it was, under the fuel tank cover, which is bolted to the tender shell in operation, thus making it impossible to gauge the amount of water being fed into the engine:









Fortunately, the fix should be fairly straightforward.  A piece of pipe sleeve soldered onto the OEM one, then run back to the desired length will do nicely.  A few mounting clamps for good measure and everything is viewable and secure. 


That'll do for now (it's early AM on the atlantic) as I need some sleep.  Here's a preview of coming attractions, or distractions if you prefer:


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## Dan Pantages (Jan 2, 2008)

Ryan 
Would you please let us know which QD's should be used? I might be making this harder than it is as I have not even seen any, but there are those of us who will be at Diamondhead where we will be able to pick up what we need. Anything else would be help also. For someone like me who is from Canada and does not have access to a lot of these parts unless I'm at a place/steam-up like DH, it sure would be a help.


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## rbednarik (Jan 2, 2008)

Dan, 

I get my QD's from either Royce or John Synnestvedt (pm me for his contact). 

For the Accucraft engines with bulkhead style fittings (CF has these), I chose to use the Rectus female fitting, male threaded M3 x 0.5 fittings on the tender and the corresponding 3mm hose barbs for extra water flow (stock lines are only 2mm ID). Simply take your 32tpi hobby saw and cut the barb off of the OEM fitting, then drill and tap for 3mm x .5 QD's. A little Silicon on the threads for good measure and your good to go.


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## rbednarik (Jan 2, 2008)

With the tender diagnosed and assembly/disassembly noted, it was time to tackle a few more points on the engine.  I noticed a loose part that could only be tightened up by removing the rear deck of the engine, aft of the smokebox.  This is accomplished with the removal of about 10 or so screws.  With that out of the way, you can gain access to the flexible steam lines on the engine should a problem occur:









The lines are an improvement over the ones used on the Garrett, which were supseptible to heat stress from the chrater hole in the smokebox.  Fortunatley, the AC-11/12 has the lines mounted away from the cheat hole (near the front of the smokebox in this case, nearest the cab).  

With that looked over, the rear engine seemed to be easy to get off of the boiler.  Not only was it easy (about a dozen screws), but the quality in which parts were made here made the total time for removal about 15-30 minutes:









A view of the engine with it's rear missing:









The rear engine is held on in two strategic spots; a saddle on the smokebox controlling the yaw of the engine through corners and a hinge pin situated between the front engine's cylinders.  Here is a view of the saddle and the mounting points for it:

















In the previous photo, you can see the flexible steam lines and their proximity to the cheat hole to allow hot water/oil to escape.  With the engine and various pipework removed, I began to dig deeper into certain items that I find crucial for a good preforming engine: cylinders, valve gear and tolerances.   The latter of which seems to be very accurate on this particular model with minimal slop and mainly friction fits for most parts.  The same goes for the bore in the cylinders.  Seems like a light honing or dressing up should true up any imperfections left, which is a defiinite improvement over the poor bore and finish that was on the GS-4 and caused some compression issues in extended running.  

There was one nitpick with this however, and that was the combination levers.  While a definite step up over the early days, they are only half the way there.   This is not to say the engine will not preform because, as demonstrated at the IE&W it can and will, BUT, since doing the GS-4's with the Argyle lever kit, I have found that effiency on the engines has increased by 1.5 to 2 fold.  Needless to say, all this is down the road a ways, but I will share my thoughts so far:

-The Radius rod and combination lever are joined to the valve block via means of an allen set screw:









-The lever which is crucial for effiecntly using steam via lap and lead of the valve (D) block, is lacking the second piviot point to allow independent motion of the valve block via the piston rod.  As it it set up now, the valve block and rod is dependent on the eccentric to control steam admission into the cylinders. 










All that aside, since I am awaiting Gordon's advice as to what should be done (is it Feburary yet??), the engine has a good strong running chassis, and should be able to handle 20-30 reefers wth ease, dependent on temperature/grades.  It will be interesting to see just what these beasts can do!

To wrap up my review thus far, here are a few photos showing the magnicifent details on this engine:


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## jfrank (Jan 2, 2008)

Great in depth review Ryan. Really appreciate you sharing all this information with us. Keep up the good work.


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## Alan in Adirondacks (Jan 2, 2008)

Ryan, 

Great analysis and series of posts. I'm a little disappointed with the combination lever situation, especially since I was the one that reported it was a working combination lever in May. I have a red face --- because in really poring over my pictures it appears to be the same setup on the prototype unit. That's the bad news... 

The good news is that with the same valve gear setup as the production models, the prototype AC-12 started and accelerated up a 0.6% grade pulling 37 Accucraft reefers! 

Now for Cabin Fever to run --- although long trains will not be the appropriate in such a venue. But wait until Dr. Rivets! 

Best regards, 

Alan


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## rbednarik (Jan 2, 2008)

Alan, 

No need to be turning red...after all, I thought that they were working as well. Don't forget, we didn't have the time to really look in-depth at the engine at Dr. Rivets, as everyone wanted to see it run! I am pleasantly surprised at the ease of disassembly on the R&D sample that is in the shop, so we'll just have to wait and see!


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## Steve S. (Jan 2, 2008)

These are some great pictures. Thanks for posting.


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## Charles (Jan 2, 2008)

General observations of QC and running capabilities:
Some base line observations of the CF runs:

1- design of the pilot.trailing trucks resulted in a problem already
2- Design of lube/steam oil results in the rear end getting the majority of steam oil-high usage of steam oil in a short period of time.
3- Burner jet clogging due to material in the housing of the jet "T" manifold
4- Tracking problem on one unit due to suspension problems
5- Great usage of water and fuel: it is a beast.

One CF did get an hour run at moderate speed with about 30 cars (forgot the actual count).

1- need to change the bolt (but not easy)
2- Lube tube change of line to a pass through.  In operations might set limit valve allowing rear engine more steam/oil than front
3- Clean, clean and clean prior to running plus disconnect fuel line to prevent liquid gas flow (gas tank also)
4- Check suspension on drivers
5- Very complex, but combination levers would help greatly


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## Pete Thornton (Jan 2, 2008)

Here's brief video of Dr Rivet and his AC-12, taken Sunday morning at Cabin Fever.  I counted about 24 reefers.


Dr Rivet at Cabin Fever 08 windows - wmv

Dr Rivet at Cabin Fever 08 Real Media -rm


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## Charles (Jan 2, 2008)

For those owners trying to get access to the jets in order to clean by removal of the cab structure:
On the cab, once you get the 4 screws off on the floor, there are three 
on the back wall holding it in place (these are the really tiny 1.7mm 
one's).  After you get all these removed, you have to pull the handrails 
out of the cab (grasp near the end of the rail and wiggle it out) then 
you should be fairly home free.  It will be a tight fit getting it back 
on, you have to squeeze the firebox lagging and then slide the cab on, 
get the little screws in first then do the 4 on the floor. 

Once the workbench is cleared of jobs we can indicate how to access
the other engine for any needs.


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