andrew jukes wrote: The vertical loads in our 1/76 scale models are indeed roughly (1/76)^3 of those on the prototype - but so are forces that result from the model’s weight. The lateral forces on a wheelset running round a curve are a function of the vehicle’s weight, the radius of the curve and (the vehicle’s speed)^2. This means that for a vehicle running at a scale speed on a curve of an appropriate scale radius for that speed, the lateral forces on a wheelset are proportionately 1/76 lower than simple scaling would suggest. We take advantage of this by running trains relatively too fast on curves of modest radius (100mph on 1.4m radius in my case).
In this thread we discussed (at length!!) the need for Gauge Widening, and went on to discuss the related topic of under what circumstance the flange on the leading wheel into a curve will try to climb the outer rail. In that discussion we were never able to explain the observable fact that model trains happily go round curves at far greater scale speed than the prototype. Thank you Andrew for pointing out what we missed.
If you have just read the preceding few post on the performance of 6 wheel coaches and would like additional information, you will also find further relevant material by following the link to Andrews original post at the top of this and then reading forward.