May/June issue of The O Scale Resource Magazine is out

[Roy]

I read and re-read the article. I think the point he is trying to make is that our cars pick up a lot of drag going around corners with RP-25 wheels and that is why we generally need far more power than the trains should justify. His wheels are apparently engineered to reduce drag in turns which allows the train to be longer.

I don't think so. Any wheel form will cause drag on turns, if both wheels are locked to the axle. Probably the worst wheel form, from the drag standpoint, are Lionel's fast angle wheels, because of the wedging action - but you two railers don't even use those.

It's true that wheel form can make a difference on extremely wide turns, but our layouts don't even come close to having the wide curvature I'm speaking of.

[sarge]

Tad has been banging on about this for at least a decade; was it Tom Fogle who used to bring him to shows when he came over from Japan?

Anyway, too many unsaids and undones here as a technical paper to sell me on the need.

Think in three dimensions, and you realise a lot of friction comes from the fact the axis of rotation of the wheelsets are offset from the bolster pin, so they don't follow a curve normal to the curvature. As the curve sharpens its easy to picture the front of the flange outside digging into the railhead and the rear of the flange on the wheel opposite dragging against the inside rail in the front wheel if a truck and the opposite on the rear wheel. The effect gets easier to replicate as the truck wheelbase increases. There is a lot more here, such as fillet behaviour, wheel-scrubbing for being off-axis, but no- one needs the complexity here to get the point. Tad isn't thinking in three dimensions, so stuck on flange angle, and his drawings and thought process reflect it. We discussed it years ago and he really didn't get the three dimensional problem then and wasn't very receptive.

He also isn't considering rail profile, material (other than the steel he uses), or dimension changes due to wear in his conclusions. Its all about the relationship between wheel and rail, not just the wheel, when considering friction or any other behaviour. He skipped half the equation.

I'm not convinced the uncertainties in his measurements don't actually exceed his reported results. I am pretty comfortable his numeric results aren't repeatable simply because there are too many variables not considered.

But, none of it really matters, because he's attempting to solve something the vast majority of us don't have as a problem (drag of wheels a limitation on 100-plus car trains) and conditions (broad curvatures, for only one). I hope no-one really takes this as a need for another standard for wheels, since it doesn't improve appearance and there is absolutely no evidence it improves track-holding, what really is important for the majority's applications.

I don't doubt he believes it does work for him, but he is operating on the fringe from most of us and there are too many parameters unstated and effects unconsidered to change standards for mainstream use.

[sarge]

The following is offered with tongue lodged in cheek...

On a totally more personal subject, I don't buy the assertion as fact the Athearn truck is the "best truck in the world". Grin!

I prefer the Intermountain Bettendorf to Athearn, myself. Same rolling behaviour, nicely equalised when properly assembled, much nicer appearance of the springs than the working ones on Athearn.

Those who want to throw theirs' away and use Athearn, throw 'em my way!

Not just Intermountain, but there are some truly lovely trucks out there that can compete for best truck in American O Scale, and I'm not sure the rest of the world and the rest of the scales don't have a few competitors of their own for "best in the world".

Grin!

[Jay Criswell]

.....but, in the end, does it really matter? Our models shouldn't pull more than the prototype. At some point, the whole thing gets silly. I think we've reached said point!

Jay

[Rufus T. Firefly]

At some point, the whole thing gets silly. I think we've reached said point!

Actually, on silliness, we may be right where we started; right with the Orouboros inside a Klein bottle folded into a tesseract run through an inversion point.

[Seaboard Air Line Fan]

If he wants he can send me 6 cars with these wheels/trucks and I'll pull them behind one of my battery-powered steamers. I'll measure the run time I get and compare it against a 6 of my cars with a variety of wheels/trucks and see if the decreased drag gives me longer run time

[Jay Criswell]

....or not.

[webenda]

At last, discussion on a technical subject, wheel friction on rails.

I will join you nit pickers with my own nit.

Tad uses “oz. wt.” as units of force. Incorrect unit! The unit of force in ounces is “ounce-force” or properly abbreviated, “ozf”.

I'm not convinced the uncertainties in his measurements don't actually exceed his reported results. I am pretty comfortable his numeric results aren't repeatable simply because there are too many variables not considered.

Well, Tad did say, “To measure the resistance is very hard.” Unfortunately he does not say what force gauge he used, just, “A pull meter was set on a flatcar.” Never-the-less, unlike you Sarge, I believe the relative measurements on the 72 inch radius (O-144 in my world) show a significant improvement over the RP26 wheel profile. And, of course, significant for his track profile only (agree on that point.) I suspect those wheels would have lots of flange rub on my tubular rail. They might even climb right off the track. [Speculation]

As far as “repeatable” -- variation is a good thing, it allows for statistical analysis of the measurement data (something Tad did not offer in the article.)

.....but, in the end, does it really matter?
Jay

Of course, it does not matter [opinion]… it is just fun to talk about. Or maybe fun to purchase some of his wheel sets and brag about your trains having Low-D wheels.

[Rufus T. Firefly]

I'm not convinced the uncertainties in his measurements don't actually exceed his reported results. I am pretty comfortable his numeric results aren't repeatable simply because there are too many variables not considered.

Lack of statistical analysis
Lack of appropriate controls
Lack of impact
Descriptive incremental science

Rejected w/o review - Triaged.

Next!

[up148]

I admire Tads passion and commitment and appreciate knowing his point of view, but felt the same way as most of you are stating. Sort of "that's nice", but you've crossed the line of diminishing returns when it comes to investment in my rolling stock. I can think of many more upgrades I can do before switching to low "D" wheels.

BH

[texas&pacific]

The completed four part series by Bill Basden of Delta Models on his award winning and and jaw-droppingly beautiful Texas & Pacific Baggage Dormitory Car was exquisite. My hat is off to you, sir! I hope to see the actual model someday.
Thank you so much Bill, for taking the time to document your workshop and modeling process. It sets the bar for outstanding craftsmanship to strive for.
As for the prototype selection, your choice of models can only be surpassed by the Sports Illustrated Swimsuit Edition. Can't wait for the Dome.
No bias here. 'Nuff said.