Which steam engines have the smallest diameter drivers?

Generally:

passenger locomotives have larger drivers to achieve high speed

freight locomotives have smaller drivers to start a long train going

yard switchers have the smallest drivers.

Railroads operating in large elevation changes would typically have smaller drivers.

Railroads operating at about sea level could go with larger drivers.

IMO, the Lionel RTR 0-8-0s with the full/upgraded drive gear (there is a "base" model and an upgrade model) has lots. I assume the Legacy and TMCC 0-8-0s are either the same or very close to the same tooling and drive train if command control/scale pieces are a requirement.

The PRR A5 0-4-0 probably had some of the smallest drivers for a switcher locomotive.  Either that or the Reading 0-4-0 camelbacks.  Generally speaking, but not always completely true the diameter of the wheel of steam locomotive was a pretty good indicator of it's approximate maximum speed.  There are of course exceptions. 

Thanks SJC I'll take a look at those.

fast freight posted:

    So which steam engines give a good side rod action without eating up real estate to quickly?

anything designed to haul logs around tight turns.... Heislers, Climaxes , Shays, Willamettes.  technically more like good "valve gear" action since only the Climax had side rods, but they are definitely slow.

Some of the little narrow gauge tank engines have driver diameters less than 20".

This is the 15" gauge "Ella" of the Duffield Bank Railway in England, an experiment in "minimum gauge" railroading.

She had an axle rotation system for tight curves, and her driver diameter was 13 1/2". There are O9 models out there, running O scale on N scale track gauge.

Y6 B's were a big powerful, I think the most powerful articulated had small drivers, it's sort of like low gearing on a car. They hauled heavy long coal trains.

For small drivers alone the MTH PRR Baby Turbine is hard to beat. 

Dennis Rempel posted:

Y6 B's were a big powerful, I think the most powerful articulated had small drivers, it's sort of like low gearing on a car. They hauled heavy long coal trains.

The N&W Y6b's were built with 57" drivers, but later increased to 58". Those are fairly small drivers.

For a project, l'd like to know what is a power unit in three rail, with: smallest spoked drivers, shortest spoked wheel base, and most compact package.  Some of the 3 rail 0-4-0 chasses out there in junk boxes have drivers big enough to model the 999.

Firewood posted:

This is the 15" gauge "Ella" of the Duffield Bank Railway in England, an experiment in "minimum gauge" railroading.

She had an axle rotation system for tight curves, and her driver diameter was 13 1/2". There are O9 models out there, running O scale on N scale track gauge.

Excellent!  I was wondering if anyone would mention the estate railways that were so common in the UK.  I get a quarterly magazine from Wales that is called Narrow Gauge and Industrial Rail Model Journal.  It is packed with models of this type.  

Lou N

Lou N posted:

Firewood posted:

This is the 15" gauge "Ella" of the Duffield Bank Railway in England, an experiment in "minimum gauge" railroading.

She had an axle rotation system for tight curves, and her driver diameter was 13 1/2". There are O9 models out there, running O scale on N scale track gauge.

Excellent!  I was wondering if anyone would mention the estate railways that were so common in the UK.  I get a quarterly magazine from Wales that is called Narrow Gauge and Industrial Rail Model Journal.  It is packed with models of this type.  

Lou N

If we try to stick with engines built as working girls and not miniatures, the old estate railways are certainly the place to look. I think the longest-lived one is the 0-8-2 'River Irt' on the 15" ga. Ravenglass & Eskdale Ry in Northern England. She started life as an 0-8-0T in the 1890s and still has much of the running gear. Driver dia. is about 18". She also has the radial axle system.

http://4.bp.blogspot.com/-Mw1Q...A/s1600/S1080025.JPG

http://rerps.co.uk/locomotive/river-irt/

     Thanks all for your replies.

      The baby turbine needs some oiler linkage with the drive rods but if the real turbine didn't have them I understand why a model wouldn't either.

      So it looks like it's either a small switcher or a large articulated.

       looks like kitbashing  a one of a kind steamer may be in my future.

                                                                                         thanks again, Dan

How about the Russian decapod from MTH? Tiny 52" drivers, beautifully detailed locomotive. Sounds fantastic. I've got the Western Maryland version and I love it. 

        Thank you Ben for pointing out the decapod.

        That maybe what I'm looking for. Always liked the looks of long range tenders as well.

                                                                        Thanks again Dan

Baltimore & Ohio's Baldwin C-16 0-4-0T switcher, commonly called the Docksider or Little Joe, had 46-inch drivers.

The locomotive has been modeled by several manufacturers in O -- mostly brass, but MTH produced a diecast version for several years beginning in 1999. Here's mine at work on my layout: