2nd Radius curves?

QUOTE (Sir Galahad @ 29 Oct 2007, 08:30) <{POST_SNAPBACK}>Is there a fix?

Third radius?

Seriously I don't have one currently but none of my friends have mentioned it.

HI-Larious...

I mean, the track is down. Forgot to mention.

This tends to affect locos with traction tyres on smaller wheels. Is your Mallard an older Hornby tender drive version?

The sideways force on the outer flange when a loco enters curved track will put additional strain on the motor. Beyond this traction tyres are very grippy and the the lateral forces imposed on traction tyred wheels in corners also put additional strain on the motor as the wheels are going to slip a lot less that those fitted without traction tyres to compensate.

Also small wheels are affected much greater than big wheels so modern outline and tender drive steam outline with traction tyres will suffer the most.

One solution is to increase weight as increased mass reduces the effect of the lateral forces on the wheels. This though can be difficult on steam locos with tender drive but less so on modern outline. Once the mass is increased you can then replace the traction tyred axles as the hauling power of your heavier loco should not drop significantly in these circumstances..

Happy modelling
Gary

You are up against laws of physics as Ravenser wrote. But despair ye not, because railway modelling is in part about engineering, much of which is about understanding the problem, then finding a way of overcoming or mitigating its' effect.

The Back-EMF facility found in both DC feedback controllers, and the better DCC decoders, offers at least part of the solution. This technique attempts to keep the motor turning at constant speed when the load varies. If that does the job then you are sorted.

However, if the load behind the loco is enough that the driven wheels slip badly when on the curve you may still not maintain speed. To overcome that requires more weight on the driven wheels. That will usually be enough to do the job.

If speed is still not maintained then either the power supply system or the motor capability may not be up to the job. In which case operate long enough applying the stress, and one of the components will fail. Replace failure with a higher grade component (this is a very respectable technique, and was the principal basis of leading edge aviation development until relatively recently!).