# 3 truck shay radius help!



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

Bachmann says the (_recommended) dia. curve for the 55 ton is 7 ft, but wat is the minimum _that it can run on without modification (i have 5 ft dia curves.


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## Greg Elmassian (Jan 3, 2008)

depends on the direction, the driveshafts tend to fall out unless they are on the inside of the curve...


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## Nick Jr (Jan 2, 2008)

Tom, I'd stick with the manufacturers directions. May I add, if the drive shafts are on the inside of the curve they probably may not let the truck swivel enough and it will derail. I'm sure Bachmann did research to see what the best drive shaft length will be best for the tightest curve possible, both inside and outside. Thank You


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## chuck n (Jan 2, 2008)

I'm wondering if the problem is with the third truck. Bachmann's website says the climax is OK for 4' diameter and larger. I believe that the 2 truck shay can also handle 4' diameter curves.

Try running it around your track holding the third truck off the rails and see if it will handle your curves. You may have to disengage and remove the trailing bunker.

Chuck


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## Gary Armitstead (Jan 2, 2008)

I have a friend who has the 55 ton, 3-truck shay (Russ Rutalj-MLS member) and when he first got it, he tried to run it on 4 foot radius curves. It didn't run well at all. The drive shaft was constantly binding. When we designed his new elevated layout, he used 7-1/2 ft. radius curves MINIMUM. It now runs great. Just sayin'.


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## East Broad Top (Dec 29, 2007)

Gary, is that radius or diameter?

Later,

K


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## Gary Armitstead (Jan 2, 2008)

Kevin,

Please re-read my post.


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## livesteam53 (Jan 4, 2008)

Tight curves are never good. 
Go as large as you can or redesign your layout.


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## Greg Elmassian (Jan 3, 2008)

Gary, I actually had the same question as Kevin, 4 foot radius should have been fine, I've seen them on tighter curves.

That seems wrong somehow, I've seen 2 truck ones on very tight curves, but I have not personally run a 3 truck on tight curves.

Greg


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## Gary Armitstead (Jan 2, 2008)

Greg Elmassian said:


> Gary, I actually had the same question as Kevin, 4 foot radius should have been fine, I've seen them on tighter curves.
> 
> That seems wrong somehow, I've seen 2 truck ones on very tight curves, but I have not personally run a 3 truck on tight curves.
> 
> Greg


Greg,

Not to "flog" a dead horse here, but Russ and I HAVE run a 3-truck shay on 4 foot RADII and it doesn't do well at all. Runs beautifully on Russ' 7-1/2 ft. RADIUS curves on his layout. A two-truck and a three-truck are totally different locomotives when it comes to radii. Just quoting facts and experience, not conjecture. Just sayin'.


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## Greg Elmassian (Jan 3, 2008)

Gary, I believe you. That is quite surprising considering the performance of the 2 truck. Can you comment on why you think this is?

I'd be guessing the third truck coupling or drive or both.

Always ready to learn, and there's no better knowledge than your first hand knowledge.

Greg


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## Gary Armitstead (Jan 2, 2008)

Greg Elmassian said:


> Gary, I believe you. That is quite surprising considering the performance of the 2 truck. Can you comment on why you think this is?
> 
> I'd be guessing the third truck coupling or drive or both.
> 
> ...


Greg,

Russ and I didn't go any further with the reason why it was binding. Our thought was maybe the third truck was the problem. At that time neither Russ or I were familiar with how shays would normally act on 4 ft. radii. This was probably about 2009 or 2010. He had just purchased the engine (this was HIS first purchase of a LS locomotive). I had quite a bit of LGB 4 footers (radius.......brand new at that!) and he wanted to try it out. No need to tell you he was just a little disappointed to see how it ran. I drew up some plans for his new elevated layout and recommended he use 90 inch radius to go with the Sunset Valley turnouts he wanted to buy. The turnouts were all 90 inch radius. When we finally finished the layout, he grabbed his new shay, crossed his fingers and put it on the track. Ran very smoothly all the way around. Not one bit of binding or any "jerky" motion. We BOTH had to assume that the loco would run better on broader curves. Because it ran so well, we never went any further to research the binding problem. It wasn't "broke" so we didn't "fix' it.  I wish I could tell you more. Hopefully someone else has an answer for you OR we were just "lucky".


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## East Broad Top (Dec 29, 2007)

Gary, like Greg, I've seen the 3-truck Shays running on 4' radius curves at our club displays. Dave Goodson's _Garden Railways_ review of the 3-truck shay states it will handle a 2' radius(!) in both directions without problems (June 2007). I've had a few 3-truck Shays cross my workbench for R/C installs, and I've not seen anything which would indicate they can't handle tight radii. I haven't tested them on anything tighter than my 5' radius curves because I wasn't asked to, so I can't say for certain that they would run free, but in just moving things about on the workbench, there's a good bit of swing there. 

To echo Greg's comments, I have no reason to doubt your experiences, but at the same time it seems out of place relative to those of others. I hope you can understand my confusion with regard to wondering whether you were referring to radius or diameter. 

Later,

K


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## jbwilcox (Jan 2, 2008)

Ian't 4 foot radius the same as 8 foot diameter?

It is hard to believe that the shay will not run well on curves as large as 8 food DIAMETER.


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## Gary Armitstead (Jan 2, 2008)

Both Greg and Kevin,

I am a retired die sinker/tool and die maker with 40 plus years in my trade and the aerospace industry. I definitely know the difference between radius and diameter. NO confusion on MY part. 

The experience Russ and I had five years ago with his particular 55 ton, 3-truck was EXACTLY the way I described. Be perplexed. NOT my problem.


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## Nick Jr (Jan 2, 2008)

Since I am the proud owner of both the 2 and 3 truck Bachmann Shay I took pics of them sitting on their respective shelves.
As you can see they both have the same space between the inner and outer drive shafts on the main locomotive. The third truck seems to have more space between the inner and outer shaft allowing it to navigate. I think that is because of the distance between the third truck and the main loco, of course that may be depending on the distance of the connecting bolster. From that I would think the minimum curve Diameter or Radius of each is the same.
I hope I have helped in some way, and if more pics are requested I will oblige. Thank You


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