I was sent this by a fellow modeller who is not a forum member, so I thought I would share it. Click on the ‘Watch on YouTube’ icon on the lower left to view the full screen:
Dave
Well, kinda OT here,
but if model railroad wheels are shaped even close to correctly, the outer edge of the wheel should not come close to touching the opposing rail in a turnout frog. Since it doesn’t even touch the outer edge of the rail its riding on.
Carry on with your regulary scheduled topic…
I did some calculations, and it appears the differential action fails at an HO radius between 165" and 330".
That means that for HO trains, the flanges are needed in curves sharper than the above.
Ed
Feynman and Wickens both handled this better.
I can’t imagine why one of the resident camera mavens hasn’t rigged up an appropriate combination of optics to actually watch what the wheels and truck frames actually do as they go around layout curves.
Hint.
I watched that video a couple nights ago. Drawings, paper cups, and computer animation looks good. In real life that flange plays a huge part. I’ve seen wheels pass inspection with a dished running surface. Also there is hundreds of miles of track that is not round on top and lots of track with a taper to the inside negating the wheel taper. Flange squeal, and sliding wheels is just what they have to deal with. Broad curves can’t be everywhere.
The differential action of the conical wheel treads on a solid axle is countered by superelevation. For any differential action to occur the truck must ride up towards the outside rail of the curve which superelevation is designed to inhibit.
Also, differential action would be very limited and depend on both the conical section and the difference between track gauge and the axle gauge between the outside faces of the flanges. For model trains this difference is much higher than for prototype. I don’t know how the conical sections compare but I suspect model wheels are much more tapered than the prototype. Model train wheel flanges are much more prone to climb out of the gauge than prototype.
The conical section tends to keep the axle centered in the track gauge, its primary function. I am sceptical that any differential action in curves would be reliable enough over a wide enough speed range to be significant in reducing rail or wheel wear. One indicator of the importance of differential action would be any difference in conical section between very high speed passenger trains like the TGV as compared to freight car wheels. Any dragging or skidding of the wheels due to an inadequate differential ratio would be far more serious at high speeds.
At the limit of the outside of the gauge a tapered flange would raise the differential effect on the outside wheel at a very steep rate tending to center the axle toward the center of the gauge at a suddenly higher rate.
Dave: thanks for sharing that video. It was well worth a watch.
-Kevin
+1
I was about to say the same thing. Great info I never knew.
So…why is the writing backwards on the video???
Hi BigJim,
I don’t see any backwards writing when I view the video. Can you describe what you are seeing in more detail?
Dave
The last set of frames reverses the image of the train, presumably to provide a semblance of variety. Someone forgot to also mirror image the ICE letters on the locomotive cab. They appear mirror image because the video image was just reversed and not mirrored.