Minimum radius for 2 ft. gauge

Discuss park gauge trains and large scale miniature railways having track gauges from 8" to 24" gauge and designed at scales of 2" to the foot or greater - whether modeled for personal use, or purpose built for amusement park operation or private railroading.

Moderators: Glenn Brooks, Harold_V

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Topics may include: antique park gauge train restoration, preservation, and history; building new grand scale equipment from scratch; large scale miniature railway construction, maintenance, and safe operation; fallen flags; track, gauge, and equipment standards; grand scale vendor offerings; and, compiling an on-line motive power roster.
James Powell
Posts: 503
Joined: Fri Oct 28, 2011 10:42 pm

Re: Minimum radius for 2 ft. gauge

Post by James Powell »

Bill Shields wrote: Sun Dec 05, 2021 10:23 pm
Statfold barn rwy in the UK.
Now.

Was at Langstaff, Ontario. Private 2' gauge railway around the house. That's my dad closest the camera, and the hired man (* I know who he is...) on the other side, photo probably taken by Charles Matthews. The curves were something like 20' radius. This is layout #2 for that location, the original was apparently just a straight up and back down in the back. The other two 2' gauge locos had been run on that, King of Scarlets/Maid Marion had a MCCR certificate issued in the 1960's.

https://www.google.com/maps/@43.8364663 ... 312!8i6656

(I'd not post the location if it was still active, but it's not...)
Glenn Brooks
Posts: 2929
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Minimum radius for 2 ft. gauge

Post by Glenn Brooks »

Our RR planning group was just reviewing minimum radius standards for our new 15” ga club RR, this past week. Came up with a significantly larger radius than we first envisioned. Mainly has to do with the track standard and size/scale of the engines we might wish to invite, or add to our roster for future use on the RoW.

We are focusing on promoting 1/4 and 1/3rd scale (2.5” - 4”) scale for member owned equipment. It’s smaller and more affordable for individual club member ownership. Some of these small engines can easily negotiate radius as small as 20-30’.

However, we realized that traditional 15” track standards calls for 5” scale equipment. These have significantly wider and deeper wheel flanges than 3” or 4” scale wheel sets. That also means they have larger wheel base and weight,,etc. so we jumped our minimum planning estimate of 45’ radius up to 85’ for freight yard sidings and 100’ minimum for the mainline.

This because we know we want to host annual invitational steam ups once we get reasonably built out. Many of the other 15” ga railways around the country have the larger track standard wheel sets. We want to attract them to participate. If the trackage and radius is to small, they wont be able to negotiate our switches, and likely will never show up... hence we choose this new minimum radius based on future operational needs, rather than present day mechanical requirements.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
thunderskunk
Posts: 109
Joined: Mon Jul 31, 2017 8:24 pm
Location: Vermont

Re: Minimum radius for 2 ft. gauge

Post by thunderskunk »

Glenn Brooks wrote: Sat Aug 28, 2021 11:47 pm Here is an informative and similar thread.

http://www.chaski.org/homemachinist/vie ... hp?t=94864

It’s a quick read as only 5 or 6 replies. The essence is, the trailing truck can disproportionately increase minimum turning radius.

Also, a quick rule of thumb mentioned is: wheelbase (W) times 20 = minimum turning radius (R)

So in your case - 34” x20 = 680”
Or, R= 56.7’.

A respectable minimum turning radius considering 20” drivers, which implies a fairly large locomotive- in the 4” (1/3 rd) scale class.

BTW, I recently acquired Ben Hammer’s complete pattern set for casting parts for his 4” scale 4-4-0 American. The drivers are 20” diameter spoked wheels. Could also be used for an Atlantic 4-4-2 in similar scale and gauge.

C2346FBF-5246-4649-BA6D-C8309457AAD8.jpeg

A014D7AA-AD1D-406B-B6AE-E7D75E7C65BA.jpeg

5D8402AE-131E-4BF7-BEE0-9EA15FC11A24.jpeg


Glenn
That… is an absolutely beautiful 4-4-0. Any posts/web pages that tell its story?
"We'll cross that bridge once we realize nobody ever built one."
djjh87
Posts: 400
Joined: Tue Apr 29, 2008 5:32 pm
Location: florida

Re: Minimum radius for 2 ft. gauge

Post by djjh87 »

Glenn
PM sent Jim
No problems just solutions.
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