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maximum fixed wheelbase for 7 1/4

keith

Joined: 1-01-70

Topics: 1

Replies: 0

Posted: Sat 30th Oct 2010, 11:19pm
maximum fixed wheelbase for 7 1/4

I would like to know what members consider the maximum wheelbase that is OK on the typical average 7 1/4 track . I am building a freelance 0-8-0 and would like the fixed base to be around 20 -24"
so would I need movement in the two centre axles, or thin the flanges down? I have narrow gauge profiles, so there is plenty to lose and still have a flange.
 

Replies To This Post

Xz

Joined: 1-01-92

Topics: 17

Replies: 244

Posted: Sun 31st Oct 2010, 5:06pm

Keith, how long is a piece of string? Your problem is not totally centred around the wheelbase, but also around the track that you wish to run on. Clearly if the track was dead straight your wheelbase could be as long as you liked.

There are a few ways that you can achieve what you need. You can thin the centre flanges, but that might make them vulnerable to damage. You could remove the flange completely from one axle especially with N/gauge profile. You can allow some side float on ALL the axles, which is the usual way to go. What you do need to do is decide what is the minimum radius that you want to traverse and work from there. Four axles will require very slightly less side float than three axles. My current build is 20" fixed wheelbase and requires 3/16" side float to negotiate a 30ft radius without allowance any for track gauge widening.
 

Xz

Joined: 1-01-92

Topics: 17

Replies: 244

Posted: Sun 31st Oct 2010, 5:07pm

Sorry! Should have added that I have three axles.
 

craiggluyas

Joined: 1-01-70

Topics: 0

Replies: 10

Posted: Sun 31st Oct 2010, 5:53pm

Keith,
I used to help operate a 0-8-0 loco with a 22" wheelbase, all flanges and no major sideplay allowance and it could go around 25' radius curves with ease. The best way to see how much sideplay would be required is to draw it out to scale.

Craig
 

Tim Martin

Joined: 1-01-70

Topics: 1

Replies: 10

Posted: Sun 31st Oct 2010, 9:09pm

If you send Trevor Collier a member of this society an Email he has a graph that lays out rigid wheel base over given radius's.
 
 
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