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Author Topic: Minimum Radius  (Read 5574 times)

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« on: July 15, 2008, 07:49:27 PM »

I have already made this suggestion on the Large Scale forum.
Please Mr Bachmann could you include the minimum recommended radius for your locomotives and rolling stock in the specifications when announcing new products and/or in the catalogue.
Jim Banner

Enjoying electric model railroading since 1950.

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« Reply #1 on: July 20, 2008, 12:11:21 PM »

The problem, as I see it, is that minimum radius for you may differ from minimum radius for me, even for the same locomotive.  Suppose you have fine track laying skills that allow you to lay the occasional tight corner that you can gently ease your locomotive around.  For you, that would be your minimum radius.  On the other hand, I might be stuck with an oval of sectional track and a kid who loves speedy trains.  Even though I have the same locomotive, my minimum radius would  be larger, possibly much larger, than yours.

We haven't even considered the other guy who starts off with the same locomotive and tinkers with it until it will negotiate even tighter curves than either of us would dare to try.

So if Bachmann were to specify what your skills allow you to use as the minimum radius, they could end up with outraged customers like me who couldn't keep their locomotive on the rails.  And if they specified what I need as the minimum radius, more skilled modellers like you might shun a perfectly good locomotive.  As for that other guy, the information would be of very little help to him as he is going to set his own specifications anyway.

Growing older is mandatory but growing up is optional.

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« Reply #2 on: July 20, 2008, 02:47:36 PM »

   Ok guys, here you go....Minimum radius allowable for Bachmann and other On30 Motive Power and Rolling Stock, courtesy of the On30 Conspiracy and Professor Klyzlr...It is a long one, but, without a doubt the best one.

On30 Commercial Loco and Car
Minimum Radius Guide

This guide was created in response to the many requests from newcomers to the scale of
On30 (1/4” scale models running on 16.5mm track), as to the minimum radius required
from various manufacturer’s unmodified locos and cars. This is not intended to be a “Last
Word” on minimum radii requirements for On30, it is intended to be more of a “Useful

As always, these results are not set in concrete, (“your mileage may vary”), but have been
collated from a volunteer pool of over 1500 members on the On30Conspiracy
YahooGroups email list. (Special Thanks to “Stumpy” Stone, Bobber Gibbs, and Dallas
Mallerich). These stats are based on locos and equipment as straight out of the box. Most
equipment can be configured and/or modified to turn tighter than the manufacturer ever
intended. However, it is the “out of the box” stats that will be most helpful to the

N.B. These stats also do not take into account such variables as track design, rail
code/height, point/switch design, “trackplan”, or “quality” of track installation. (I
personally use handlaid track on a “nominal” 18” radius. “Nominal”, because it is truly
handlaid, and hence is not of a perfect constant radius throughout the curve).
N.B. These stats do not take into account any particular combination of coupled
equipment. IE a 4 wheel Porter loco and 4 wheel skips may stay coupled around a given
curve, but a Mogul on the same curve may drag the same 4 wheel skips sideways to the
point of skewing them off the track.
The “Practical Operating Radius” specs are known to work with each piece of
equipment listed.

The “Absolute Minimum Reported Radius” info is the lowest successful radius reported,
curve radius gets tighter, the more critical it becomes to make sure that your trackwork
and rollingstock is mechanically perfect. If you are prone to taking shortcuts when laying
your track and tuning locos/cars, or are not mechanically inclined, do yourself a favor,
don’t “push the envelope”, try to get the largest “Minimum Radius” you can.

Use these stats as a guide, but always consider the manufacturer’s design limits when
designing a layout around certain pieces of equipment. Remember, a layout which will
only ever run Bachmann 4 wheel Porter Locos and 4 wheel skips may be able to get away
with 6” radius curves, a layout which will occasionally play host to PSC K27 locos will

Happy Modelling,
Aim to Improve,
“Professor Klyzlr”

“…Still hauling logs with a Class A Climax and log bogies, deep in the Aussie Bush…”

On30 Practical Minimum Radius Guide Page 1
Copyright Professor Klyzlr 2007

Manufacturer / Equipment Practical
Bachmann (Recommend 18” for all equipment)
2-6-0 Mogul 18” 12”
0-4-0 Porter 12” 6”
0-4-2 Porter 15” 9”
0-4-0 Davenport Diesel 12” 6”
2 truck Class A Shay 18” 15”
2 truck Class B Climax 18” 12”
Closed Street Car 15” 3”
2-8-0 Baldwin Outside Frame Consolidation
- 15” has been reported, with PERFECT TRACKWORK
- 12” has been reported when
the tender is connected by 2nd Drawbar hole,
This is a LARGE LOCO, Mechanically and Visually
you push the minimum radius limits at your own risk!
PLEASE Re-Read Page One of this document.
22” 18”*
Railtruck (Leading bogie/Single powered trailing axle) 18” 12”
2-4-4 Forney Inside & Outside frame versions
* NOTE: While the Forney is not a Large loco, the forney
design has a rear coupler configuration which will swing a
LONG WAY off track centerline. This MAY result in the
Forney dragging some shorter rollingstock sideways off the
track on < 18” radii curves.
22” 18”*
Boulder Valley Models
(Thanks to Dallas @ BVM for the official design specs!)
301/302 Dunkirk (Athearn HO SW1200 diesel mech)
NB: Will probably negotiate 15”, but coupler swing may pose
18” 15”
361/362 Mighty Midget
(4 whl power truck from B’mann HO “Phase 1/2” 44tonner)
6” 6”
371 Mudbug and Trailer
(4 whl power truck from B’mann “Brill Trolley”)
6” 6”
KD-05 Mega Midget
(4 whl power truck from B’mann HO “Phase 1/2” 44tonner)
9” 9”
351 Boxcab Diesel
(B’mann “Phase 3” 44 tonner, with central motor)
15” 15”

On30 Practical Minimum Radius Guide Page 2
Copyright Professor Klyzlr 2007

KD-01 “44Tonner Bash”
(B’mann “Phase 3” 44 tonner, with central motor)
15” 15”
KD-06 “70Tonner Bash”
(B’mann “Phase 3” 70 tonner, with central motor)
15” 15”
327 “Tin Chicken”
(B’mann HO 4 wheel Ballast vehicle mechanism)
9” 7”
251/252 APEX 14 Ton “Mini Climax” Locomotive
(B’mann HO 50 ton Class B Climax mechanism)
12” has been reported as possible by BVM, with
- removal of the front truck front brake beam, and
- clearance modifications to the Front and Rear End-beams.
18” 15” *
See Notes!!
Wiseman Model Services
(Thanks to Keith @ Wiseman Model Services for the official
design specs!)
Vertical Boiler Shay (On30 version) 18” 18”
Mich Cal #6 Shay (On30 version) 18” 16”
MOW Railtruck (On30 version) 18” 10”
Precision Scale Castings
K27 2-8-2 26” + 26” +
Precision Craft Models (BLI)
Galloping Goose 18” 18”
Broadway Limited Industries
C-16 2-8-0 18” 15”
LeeTown Models
(Thanks to Lee Snover @ LeeTown for the official design
GE Boxcab Locomotive 7.5” 5”
“Model T” railtruck 8” 8“

On30 Practical Minimum Radius Guide Page 3
Copyright Professor Klyzlr 2007

Freight/Passenger Cars
Manufacturer / Equipment Practical
Bachmann (Recommend 18” for all equipment)
Flatcar 18” 12”
Gondola 18” 12”
Boxcar 18” 12”
Stockcar 18” 12”
Tankcar 18” 12”
Passenger Coach 18” 12”
Combine 18” 12”
Baggage Car 18” 12”
Caboose 18” 12”
V Dump cars 15” 10”
Wood Side Dump cars 15” 10”
Log Skeleton cars 18” 12”
Boulder Valley Models
(Thanks to Dallas @ BVM for the official design specs!)
SC1/2 Pedestal Flats 6” 6”
501 thru 508 “Shorty Cars” 9” 9”
511 thru 513 “16-foot cars” 15” 10”
521 thru 524 “16-foot cars” 15” 10”
561 thru 564 “15 foot hopper” 15” 12”
601 thru 606 “20-foot cars” 15” 15”
607 thru 609 “20 foot cars” 15” 15”
611 thru 616 “20-foot cars” 15” 15”
617 thru 619 “20 foot cars” 15” 15”
621 thru 626 “20 foot cars” 15” 15”
631 thru 633 “20 foot cars” 15” 15”
Shorty cars 15” 6”

On30 Practical Minimum Radius Guide Page 4
Copyright Professor Klyzlr 2007


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