# Anyone rebuild Accucraft Ruby-cylinders with go-through piston valves?



## Gerd (Jan 7, 2008)

Hi folks,

I've a Accucraft 13ton Shay and as on the Ruby, the steam engine is known for the issues of inside and outside admission. My Shay is running fine in forward, but stalls badly in reverse, due to the outside admission.

My question is - did anyone ever rebuild the piston valves to go-through types, meaning to bore out the cap at the top and make new piston valves, which will get rid of the issues at all?

I know this type of piston valves from Regner locos and they worked well there. I think it's also possible on the Shay/Ruby-cylinders. At least maybe I've to make a new set of valve chests for that as well, to save the original ones.

Any experiences out there?

Regards, Gerd


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## HMeinhold (Jan 2, 2008)

Gerd,
the main problem with the Ruby type cylinders is the cutoff. When optimizing operation in forward, reverse becomes pretty bad. Bill Allen increased the diameter of the ports to increase the admission angle. We have done this with good results on Ruby type cylinders. Bill will probably reply to this thread too, otherwise I will talk to him tomorrow.
Regards


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## Dwight Ennis (Jan 2, 2008)

Dave Hottmann did an extensive article on *Inside Admission and Air Tuning a Ruby* here...

http://www.santacruzlumberco.com/MLS_PDFs/InsideAdmissionAndAirTuningARuby.pdf

While he doesn't do as you suggest, his method can make a huge difference in how a Ruby runs, Might save you a lot of work.


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## Gerd (Jan 7, 2008)

Hi Dwight,

I've Dave's pdf at hand and also checked the steam port diameters. My maine issue is, that my future garden railroad will be of a point-to-loop style and at least, I like to do a lot of switching operation. Therefore it's important to me, to get the Shay running well in both directions.

I already changed the admission as suggest by Dave, which makes the loco a good runner in forward, but not in reverse.

Gerd


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## HMeinhold (Jan 2, 2008)

Sorry guys to contradict:
The bad running in one direction is not caused by inside/outside admission. The indirect steam ports only create additional throttling, but do not severly affect the timing, which causes the problem. It is the narrow admission angle, as Bill found out. After his suggested modification, my Betsy with Accucraft valves and home-made cylinders pulls (and runs) equally well in both directions. I don't think Gerd's layout will be more challenging than this:






Regards


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## Chris Scott (Jan 2, 2008)

Dwight Ennis said:


> Dave Hottmann did an extensive article on *Inside Admission and Air Tuning a Ruby* here...
> 
> http://www.santacruzlumberco.com/MLS_PDFs/InsideAdmissionAndAirTuningARuby.pdf
> 
> While he doesn't do as you suggest, his method can make a huge difference in how a Ruby runs, Might save you a lot of work.


I have a copy of Dave' article at the end of Dwight's link above. In it Dave deals with tuning a shay beginning the section with the post below:

"Reply author: Dave Hottmann
Replied on: 26 May 2004 14:52:53
These instructions will work for Shays. The Shays are basically vertical Rubys with the main drivers being replaced by a crankshaft. Dead centers are at 12 and 6 o'clock. Two cylinders Shays can be easier than Rubys because everything is on one side. "

Might help. My copy of the article is 51 pages and the Shay section (starting with the above quote) is page 14. Dwight's .pdf file has the same number of pages.

Dave tuned my 2 and 3 cylinder shays and they ran fine forward and reverse.


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## bille1906 (May 2, 2009)

Gerd
As Henner stated, other than the shortcut taken on the valve pistin the main problem with the Ruby,Shay is that it is simple valving with way too much lap which makes the timing critical. you can either time it to run good in forward or reverse but not both. by enlarging the ports, you remove some of the lap allowing better running in both directions.
Here is a link to my fix
If this doesn't go through let me know as sometimes these MLS links just bring you to the main forum page
http://forums.mylargescale.com/18-l...our-ruby-shay-forney-run-better-than-new.html


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## Gerd (Jan 7, 2008)

Hi Bill,
the link worked fine and I read through the document.
I'll give this a try first. Maybe I'll find some time next week and I'll report from the results.
Thanks & regards, Gerd


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## lotsasteam (Jan 3, 2008)

In one of the:Gartenbahn issues someone rebuilt the piston valves with slidevalves,(Brocken loco),quite a task !


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## Gerd (Jan 7, 2008)

Good morning,

yesterday, I spend some hours to work on my Shay. First of all, it’s a challenge to get the steam engine of the Accucraft Shay apart from the rest of the loco. I had to disassemble nearly the whole loco to get there.

After an hour or so, I had the steam engine in front of me and removed the valve chests. My Shay is from the first batch (as far as I could determine, since I bought the loco second hand). The port holes turned out to be of .070 already, while the sleeve was .065.

I drilled the holes to .075 and reassembled the loco for a test run with steam. I didn’t change the valve gear setting in this step. The loco seems to run much smoother now. Fun fact, she now runs better in reverse, while she did in forward before the change. Remember, I didn’t change the valve gear setting / eccentrics so far.
What I could check in the 5 minutes steam run at 11pm, the fix seems to work.

During the next work session, I’ll do some fine tuning and adjustments to the valve gear, hopefully by equalizing the valve gear setting/performance for forward and reverse.

I’ll report my experiences once I did further progress.

Regards, Gerd


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## HMeinhold (Jan 2, 2008)

Where did you get the 0.075" drill bits in Germany or did you cheat and drill 1.9mm (as I did) .


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## Gerd (Jan 7, 2008)

You got me, Henner ;-)
I cheated as well. I did some fine tuning and now she runs smooth so far. The only stalling is on slow reverse, which cames from a worn out eccentric. I already fixed them some years ago, but not the best way, so I should go and search for some ball bearings...

Gerd


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## bille1906 (May 2, 2009)

Here you go
http://www.ebay.com/itm/5PCS-6701ZZ...mm-18mm-4mm-/261499763022?hash=item3ce299b94e


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## Gerd (Jan 7, 2008)

Hi Bill,

thanks, I already ordered some here in Germany ;-)

Here's a video of the Shay back together on another test run after the steam ports got modified. The stalling in reverse comes from the eccentrics. Once they are replaced, I look forward to a smooth running engine.






Gerd


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## Gerd (Jan 7, 2008)

Hi folks,

the eccentrics are now rebuild with ball-bearings and the valve timing ist set by air-tuning. Here's the result in different stages.






Not it's time to get the garden railroad built.

Gerd


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