nominal driver sizes

trainrobber

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Jan 21, 2003
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Don't know if this will be of any use to anyone but it may simplify some research/homework for anyone interested in achieving similar results for similar projects.

Projects: Class A/B climax & Class A/B Dunkirks
generally Class A Climax's with vertical boilers had either
26" or 28" drivers (I'm going to assume the same for the
Dunkirks) and again generally the Class B's with the
Horizontal boilers had 28", 30" and 31" drivers. This
does not cover any custom built driver assemblies.

NWSL offers miniature chassis kits as follows:
*#1218-6 HO gauge 4'-4"wb trucks
*#1219-6 HOn3 gauge 4'-4"wb trucks
*#1220-6 HOn30 gauge 4'-4"wb trucks
* all these sets can have custom wheels factory installed i.e
spoked wheels. the smallest diameter spoked wheel size
is limited to 33" because of 3/32" axle that comes with the
miniature chassis kits

Here's a few equations that might also help;

HO scale = 1/87 (25.4mm = 1")

26" = .2989" or 7.59mm
28" = .3218" or 8.17mm
30" = .3448" or 8.76mm
33" = .3793" or 9.63mm

Last but not least I checked out my MDC Shay for driver size and it's roughly got 34" drivers. I also did the MDC Climax (I believe it's supposed to be modeled after a 20 ton tee boiler) and it roughly had 41" drivers, not exactly to scale but still a nice little engine. So you can see although losing exact scale with those custom wheel sets you gain the spoked wheels which in my mind is worth it. Anyway again hopefully I didn't bore too many of you veterans with this bit of info.
 

neilmunck

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Are teh wheel sizes for standard gauge of narrow gauge?

I am guessing that they used smaller wheels on narrow gauge as I have plans in the Feb 1996 MR that shows a 3foot gauge class-C climax with 29 1/2 inch wheels but my HO scale bachmann shay has 33 inch wheels and my steam locomotive cyclopeadia has drawings of a more modern shay with 36" wheels.

the confusion:confused:
 

trainrobber

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As far as I know they don't differentiate in wheel sizes between narrow gauge and standard gauge, more as to what size (weight and so forth) the track was that the engine was going to work upon. As far as your wheel sizes on the shay's, I believe that one of the smaller if not smallest shay's ever built was at or around 12 tons and only had 21" drivers, and definately not the largest shay built but one of the bigger ones at 110 tons had drivers at 46". The sizes that I've listed only pertain to Class A and Class B locomotives.