Silicon Investor (SI) -- The First Internet Community

STOCKTALK

We've detected that you're using an ad content blocking browser plug-in or feature. Ads provide a critical source of revenue to the continued operation of Silicon Investor. We ask that you disable ad blocking while on Silicon Investor in the best interests of our community. If you are not using an ad blocker but are still receiving this message, make sure your browser's tracking protection is set to the 'standard' level.

Pastimes : Don't Ask Rambi -- Ignore unavailable to you. Want to Upgrade?

To: Ilaine who wrote (51765)	6/4/2000 12:55:00 PM
From: Jacques Chitte	Respond to of 71178

The rails and the wheels are elastic. Like extraordinarily stiff springs. The steel compresses. If we knew the modulus of elasticity of the steel, or the compressibility (which might be related numbers) we could refine this engineer's parlor game. We could figure how many thousandths the wheel and rail compress into each other before downthrust equals springback force, then use trig or something to get an area estimate. But I'm too something to look them up. In any case it's more fun not knowing and generating wild guesses.

To: Ilaine who wrote (51765)	6/4/2000 1:51:00 PM
From: Gauguin	Read Replies (2) \| Respond to of 71178

What we're trying to figure out here is the actual area of contact between the wheel at any given time, right? Exactly. Zactly, zactly, zactly. That is what interests me here first; the "prime" that it all comes from. The link between wheel and rail surface, and then the effect of weight and motion on expanding that area. Alpha and Omega. Drive force may also expand it. I don't know. Heavier cars or engines I assume will have greater contact area. Weaker or more flexible steel (or rail) would also have more area. Greater speed may decrease or increase area. Greater drive load on powered wheels may have more. But the actual area of contact under all the above conditions is a function of wheel and rail geometry. I want to separate that. That's the first place to understand, to me. THEN, once I feel like I understand that, the drive power of engines gets interesting and cleaner and easier to understand. So does the amount of flex in the rails. (We know from watching, they flex like crazy.) In the tractive ratio, it looks to me that they have skipped over the issue of contact area of wheel to track, and just delivered a generalization of power. And we can't extrapolate from inspecting the wheels on a train at rest because the rails are somewhat flexible? Seems true as well. (But maybe not; I don't know. Perhaps with some sophisticated input.) The question is accurate. They're two different conditions; with an equally weighted wheel. And then there's speed. How much effect has that, if any. The wheel is trying to turn itself round; the rolling weight is trying to compress it ever to a circle; at the same time it's trying to squish it flat at the point of bearing. How much actual "dimple" both surfaces get, interests me. Dimple is a good word for it. (Lather thought of.) The dimple is moving along the rail and circulating around the wheel. It is a very absolute area. It's either IN contact, under compression, or it is NOT. I am thinking of going to a track, hopefully where there's an engine as well as cars, and measuring the contact area. With a feeler gauge, if I can find my freaking feeler gauge. I think .001 of an inch ought to be close. (If the space is less than a thousandth of an inch, we'll call it touching. Even though it's not.) Maybe some other way of measuring, a clever way, will give us an exact foot print. We could "blue" the wheel and then have em move the train. I will have to do this on a stationary engine and car. :o) Can we call this "at rest" area of contact the static area of contact? (I am NOT an engineer, so I'm making these up.) [If all the steel of wheels and rail were the same, the variance of area would tell us the weight of the car on the wheel. But that's just consequence.] Motion of the same wheel is another, different, area. Completely different. The rail may flex more OR less ~ I don't know. (But it IS also flexing when the stopped wheel is sitting on it. Most definitely. It is "loaded.") Whether that flexion is increasing with train speed or decreasing, I don't know. If it's increasing (and I'm not sure it is), then the contact area, say the "dynamic contact area," is increasing. How much increase for the same wheel in motion? Or does it decrease? This would be fascinating to set up a simple film of proof/demonstration. A corollary, or opposite, or whatever, of this is the change in wheel shape under motion. The same thing applies. At rest, the wheel is point-loaded. Flattens a very precise way. The axle of the wheel-pair is also "centered" on the track. Both wheel cones are being loaded in the same spot, at the same diameter of their cones. (Remember the wheels are beveled. They are not cylinders. They're vertical pie tin shapes.) The wheel definitely flattens locally, when at rest. When the dimple is not revolving. So does the track. Dos dimples. That is one "given" in this whole thing. In any gavitationally affected contact between two objects. They squish each other. (And that steels differ.) That at-rest dimple we can measure. But when you start moving the wheel.....what happens? More "weighting" or less? Does the turning wheel have more dimple or less? How does increasing speed affect this? Why? Precisely why. I want data for these, and proof. NO assumptions. Before I even get to Power and Traction, I want to know what's happening. How much wheel area, footprint, do we have? To carry and deliver load. And also to provide/transfer drive at the engine. I have to break things down this way. It's my learning style. Whatever "it" is. And then I usually need to "see" the things being studied to cement it in there. A feeler gauge, and film, and things like striation patterns on the wheel, are "seeing." Whitney's fortune came from the annealing process for the wheels he invented that hardened them and allowed the trains to bear more and go faster. That's what the article says. whitneygen.org He was a partner with Matthew W. Baldwin in the Baldwin locomotive works in Philadelphia, 1852-54; was chosen president of the Morris canal company in 1854, and constructed the steam incline planes used on the canal. He invented the corrugated plate car wheel, in 1847, and began its manufacture in partnership with his son, George Whitney. In 1848 be invented a process for annealing car wheels, that increased both their speed and capacity This invention gained him a fortune and about 75,000 car wheels were annually manufactured by A. Whitney & Sons.