Locomotive minimum track radius

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Re: Locomotive minimum track radius

Post by David_T » Fri Mar 29, 2013 7:01 pm

There have been several good replies. What I remember must have been a formula for a 2 axle loco. It involved the axles center-line spacing, the track gauge and some constant value number. The results would be minimum radius in feet. Unclear was the track gauge value to be the designed gauge (like 7 1/2) or the actual rail spacing. It does make more sense to use the true rail spacing.

Cary Stewart
Posts: 542
Joined: Wed Jun 08, 2011 5:54 pm

Re: Locomotive minimum track radius

Post by Cary Stewart » Fri Mar 29, 2013 7:36 pm

From a practicle point of view and from experience comes the following.
A Railroad Supply 4-4-0 will negociate a 25 ft radius track in 7 1/2" gauge and perhaps less. However, to do that you have to increase the length of the drawbar between the engine and tender. Otherwise the corner of the tender will meet the corner of the cab and you may find yourself on the ground. The LALS track main line has minimum 60ft radius curves because of the large engines that run on it. As has been said it depends on the loco and its rigid wheel base and if it has blind drivers or not. Also possible is lateral movement in the end drivers and some time the center drivers are a little bit narrower than the ends. Lots of tricks.

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