Both will operate on well laid 12" radius, but 15" is a more reasonable
minimum. The 0-6-0T would be a problem on 12" - the long rear overhang puts
the rear coupler over the outside rail limiting what the loco can stay
coupled to. The MDC "Climax" uses the same mechanism as the 600 HP box cab
diesel, with a center drive gear that does not displace laterally on curves.
On smaller radii, the "kink" in the drive line through the U joints to the
trucks gets large, adding to the noise and vibration of operation (but then
these beasties aren't that great on straight track). Gary Q
For a complete discussion on curves and coupler effects on
all types of equipment including minimum radius, double
track clearances and easements, see first site below.
Hope this helps.
MODELRAILROAD TECHNICAL INFORMATION
NMRA has a standard practice which I find useful. RP 11 Curavature and Rolling
Stock says for a Old Time Pike, Small Branch Line and Feeder Lines with:
Steam locos to 11' ridgid wheelbase (your 0-6-0), Diesels to 40' with two
4-wheel trucks (like your climax), and
Old time passenger cars to 50' without diaphrams, and
Freight cars to 50'
In HO a 16 1/2 inch radius and # 5 turnout is acceptable.
I have a Heisler, 2-6-0 and 0-6-0s that I run on these specifications.