# Mixing Curve radius



## Flash53 (Dec 19, 2009)

I'm starting a 4 x 8' layout (actually started once, think about tearing down and restarting). My scale is HO and I've been restricted to a small layout according to the boss although I will try to design to allow for future expansion. My mind keeps going to some dogbone type of layout. I will be running small steam (4-4-0) to smaller diesels.

What I would like to know is: If I want a 180 degree curve. Can I use 22" for 90 degrees and then 18" for the other 90 degrees? My thinking is that tighter radius at the front would allow me more room at the front for a siding.

Thanks
Steve


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## sstlaure (Oct 12, 2010)

Yes....Or you can use flextrack and curve to shape. You just need to make sure there is a smooth transition from piece to piece (no kinks) I much prefer flextrack.


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## tjcruiser (Jan 10, 2010)

I agree ... you should be fine with a 4-4-0 on that.

I did half-22 and half-18 on my little HO layout ... left side, before the mountain ... radius transition is at the barn with the white sheep and tractors ...

http://www.modeltrainforum.com/gallery/files/2/2/6/7/tj_ho_train_layout_jan2010_11a.jpg

Regards,

TJ


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## jzrouterman (Nov 27, 2010)

tjcruiser said:


> I agree ... you should be fine with a 4-4-0 on that.
> 
> I did half-22 and half-18 on my little HO layout ... left side, before the mountain ... radius transition is at the barn with the white sheep and tractors ...
> 
> ...


I agree. 4-4-0s are smaller in length than GP38 diesel engines, and GP38s (as do all GP type engines) run just fine on both 18 and 22 inch radius track. 

Some SD40 engines will run on 18 inch radius track as well, though sometimes when backing, the "swing out" distance of their bodies will cause "coupler jamming" thus sometimes causing the cars directly behind them (depending on their length to derail in the process. This is especially true if the couplers of both the engine and the car are offset from each other during the spotting process.

I once had a little SW type switcher and some 36 ft cars which I ran on 15 inch radius track. The entire layout was on a 3 x 4 ft table. Though Athearn claimed the minimum radius for the cars and the engine was 18 inches, the engine and the 36 ft cars both did very well on 15. I never had any problems at all. However, if I tried to run anything larger though (in either engines or cars), the couplers would almost always jam, causing a derailment.

Routerman


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## KopyKat007 (Aug 27, 2011)

Ok pure noob question, whats the numbers like 4-4-0 mean and what do they exactly refer to?


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## Big Ed (Jun 16, 2009)

KopyKat007 said:


> Ok pure noob question, whats the numbers like 4-4-0 mean and what do they exactly refer to?



The wheel arrangement on the engine.

4-4-0 is 4 in the front 4 in the middle none under the cab.


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## tjcruiser (Jan 10, 2010)

Steam loco wheel configuration is tagged per the "Whyte" notation:

http://en.wikipedia.org/wiki/Whyte_notation

TJ


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## KopyKat007 (Aug 27, 2011)

big ed said:


> The wheel arrangement on the engine.
> 
> 4-4-0 is 4 in the front 4 in the middle none under the cab.





tjcruiser said:


> Steam loco wheel configuration is tagged per the "Whyte" notation:
> 
> http://en.wikipedia.org/wiki/Whyte_notation
> 
> TJ


Alright thanks guys


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