Why is the blue snowflake on my dash flashing? Isn't that the defrost? My 2 yr old sat in the front seat and in about two seconds locked the doors turned the key so that the headlights came on. She was rapidly pushing buttons before I could get her out. Now the blue snow flake flashes?

I am a firefighter and an not flaming you, however, I've seen several dead two year olds, including one that fell in a well and drowned.

A two year old has no business in a car outside of a child seat!

Any child that does not have a valid driver's license does not belong in a car alone for any reason. Many cars catch on fire while idling, and some even after being shut off after a ride.

I think that the blue snow flake is trying to tell you that YOU NEED TO BE FAR MORE CAREFUL WITH YOUR CHILD!

Yes, that was yelling and was intended to be judgemental.

I certainly agree that my stupidity abounds!

"...agree that my stupidity abounds!"

Not stupid. These things happen with kids, which is why they're built tough, just like Volvos. Nothing happened, nobody hurt, lesson well learned for a very cheap price -- and usually a good education costs a lot more.

Alexander Flemming (1881-1955, Nobel in '45) once left a series of Petri dishes on his windowsill to cool after an experiment. Unfortunately, the experiment was a completele failure. Rather than worry about his stupidity abounding, he asked what caused this failure. He discovered a mold called penicillium, and the rest is history.

What positive, creative learnings are here for you? And I really mean the positive learnings, not the negative ("Don't do that!") learnings.

"What positive, creative learnings are here for you?"

Something about monkeys and typewriters comes to mind, but one has to be careful, as a couple of us here on the board actually support our Volvo habits by ramdomly pushing buttons.

"...support our Volvo habits by ramdomly pushing buttons..."

Nothing wrong with that as long as you truly learn each outcome and improve from it. It's sort of a "Darwinian" method.

I remember my long-gone mother telling of the time I, as a four-year-old, stole a train. The railroad repairmen had motored down to a siding and left their electric-powered thingamajig sitting there. I jumped on and pushed the lever, and rode a mile down the tracks. The cops brought me home.

I can never resist testing a switch or lever or dial, "Gee, let's see what this does." I'm particularly attracted to the switches that say, "Don't!" and cannot avoid those that say, "Don't, you moron!"

Remember this: The people who don't make mistakes are the people who don't do anything. (I don't think its compliment is necessarily true, however. That is, I don't think that a long list a failures necessarily indicates an even longer list of accomplishments.)

"ramdomly"

Darn! I'm even better than I thought.

But seriously, when training others I tell them "We don't have a simulator, so just push it and see what happens..."

Often good for a laugh when nothing at all happens.

"Darn! I'm even better than I thought..."

I thought you were better, too. "Ram"domly, as in "randomly accidental mindlessness," or something, a clever play on words.

"We don't have a simulator, so just push it and see what happens..."

Words to live by, or whatever...

Can't top stealing a train, though. Only thing better would have been if you'd broken it...

"Only thing better would have been if you'd broken it..."

Broken it? Oh, I forgot to tell you about the bad OD relay........

I've wondered why you decided to become an engineer. Got on track and started training at a young age. Hard to believe that you reasoned it through rather than having some locomotive. Some rail against the narrow gauge of the engineer mind set, but others find ties to all sorts of useful ideas.

"...others find ties to all sorts of useful ideas..."

Before I run outta steam, it gives me something to choo on.

Speaking of railroads, do you know the physics that keeps trains centered on the rails? No, it's not the flanges.

After you caboose around awhile, I'll pass along a few hints....

I would guess that the camber of the rail bed (ie banking) would help zero out the centrifugal forces on a trail going around a bend. The bank would have to be calibrated for a specific speed. That is a first order correction. The flanges ARE necessary to provide second order nudges - which become first order of the actual train speed is different enough from the rated bank speed.

The rotation of the motor-generator set is not central to the riddle. It would set up a gyration effect that would counter any attempt to twist the engine off that axis of rotation - ye old V x F stuff that you can verify with a spinning bicycle wheel. As the resultant reaction force is perendicular to the applied force, it won't help to counter the centrigugal force. It will push the train down or up depending on the direction of the turn.

IMHO, Bill

"...camber of the rail bed (ie banking) would help zero out the centrifugal forces on a trail going around a bend...calibrated for a specific speed..."

Yes, but that's not part of this question. I think that's so the railroad riders don't get champagne splashed on their evening finery. Or whatever.

"...flanges ARE necessary to provide second order nudges..."

Not really, although they're sorta like a parking brake. Good for emergencies, and also critical for when you're not moving. If the flanges were responsible for keeping the train on the tracks, they'd be worn off in several hundred miles. And you'd hear the training coming a looooong distance off.

"...rotation of the motor-generator set is not central to the riddle..."

Right. I said that. It's totally irrelevant.

The first given clue is that the two wheels on an axle are rigidly mounted to the axle. However one wheel turns, so turns the other wheel.

The second clue, which Nappy never asked for, is equally critical -- the wheels are slightly tapered. The larger diameter is toward the center of the vehicle (and the flange). The smaller diameter is toward the outside.

Cogitate.

Ok. So the wheel 'falls' towards the centre and the whole rig seeks the low point. Also if the axle were off center, the high riding wheel would be rotating at with a larger diameter, hence speeding up that side relative to the low riding opposite wheel, thus turning the axle and the high riding wheel runs down the rail towards the inside. Cute.

You still need the bank so the train does not tip over to the outside of the curve. Plus given sufficient speed, the self-centering force could lose the battle against the centrifugal force. Self-centering or no, the wheels could slide right off the rails.

Bill

"So the wheel 'falls' towards the centre and the whole rig seeks the low point..."

No, the wheelset steers itself toward center based on the speed differential between the two wheels (which cannot exist because they're locked together).

"...high riding wheel would be rotating at with a larger diameter, hence speeding up..."

Now you got it.

"...need the bank so the train does not tip over to the outside of the curve..."

Yes, but that's a different and independant issue.

"Self-centering or no, the wheels could slide right off the rails."

No doubt. Can you imagine what would happen if you painted 5 miles of rails with grease?

This whole discussion was about the obscure but obvious physics/mechanics behind trains 'n rails 'n stuff. It wasn't about practicalities such as slippery tracks.

"the wheels are slightly tapered"

'nother words, they are both trying to turn inwards all the time. Since they are rolling at the same speed, they wind up going straight. Didn't think that the rails were canted because pennies don't slide off.

I do better with fish and boats.

"...they are both trying to turn inwards all the time..."

Not at all. Remember that they're both rigidly afixed to a rigid, solid axle.

But in your mind's eye, imagine what happens when the railroad car drifts sideways slightly. Now one wheel is riding on a slightly smaller diameter, and thus trying to go faster. The other wheel is now on a slightly larger diameter, and trying to go slower.

But both wheels are forced to rotate at the same speed because they're rigidly tied to a solid axle.

So the slower wheel is driven faster -- this has the effect of "steering" toward the center. Thus, whichever side drifts toward the outside, it becomes the steering side and the railroad car is nudged back toward the center.

You can also see that the inside wheel, which is on the smaller diameter and going faster, feels some drag from the slower wheel. Thus, it tends to steer toward itself -- which also brings the car back toward center.

This only works while in motion.

The flanges keep the car on the rails while at rest (while loading a boxcar with a forklift truck, for example). They probably also play a role going around tight curves.

Mostly right. The flanges keep the railroad car wheelset or truck, on the rails during the side to side motion which happens all too frequently. A ringing condition also can occur which would manifest itself in a continuous side to side motion. The flange prevents the wheel fron climbing over the railhead causing derailments. To prevent rail wear on curves, oilers are used to add grease to the rail. This does not go on the railhead but on the side of the rail and on the flange. Nothing is perfect though. Wheelsets are turned on a lathe to true them up, so to speak. The wheel is bell shaped so an audible ring does occur, Horseshoe Curve on the old Pennsy mail like west of Altoona PA. is a prime examble, and it can be really LOUD!!!

NMRA RP-25 dictates the shape of model RR wheels. See NMRA RP-25 for a visual indication.

Nuff said...

Those dimensions look like model railroad stuff, or maybe I can't read it right....

Flight of the Phoenix.

Ah, yes. Model airplanes require more precision and more engineering than the real thing. OTOH, it's easier 'n cheaper to recover from a derailment with a model than with the real thing.

Now I'll go back to avoiding speculation as to the best use for an oil drain plug that has been made obsolete by the "Foster Self Change" method of crankcase maintenance. You probably need a nap.

"...as to the best use for an oil drain plug that has been made obsolete by the "Foster Self Change" method of crankcase maintenance..."

Actually, I use magnetic plugs from IPD on all my cars.

"You probably need a nap..."

Yeah, but you-know-who says it's time to buy a tree and wreaths. I hate this *&$%#@ time of year.

"hate this *&$%#@ time of year"

If you do this right, you ought to be able to get a new chainsaw out of the deal. Wazza problem with that?

If I do this right I should be able to get a ne XC outta this. Or even an old one.

Hell, I don't need another chainsaw -- I haven't used the other one in 4-5 years.

What I really want outta this is a quiet Sunday afternoon nap, just like you said.

A new XC? I guess that would justify a 24x40 garage with a lift and a machine shop. Also a Radio Shack franchise. Always thinking....

Maybe a package store too.

The package store is guaranteed to be successful. The Radio Shack, maybe...

"physics that keeps trains centered on the rails"

Deep thinker that I am, I figured it had to do with gravity. Otherwise they could make trains out of space-age composites and save enough energy that they could compete with the trucking industry.

My friend Slugger works up north in the locomotive sheds setting wheel alignment. He uses a real BFH.

Ok, is it sort of like the same reason that motorcycles only tip over when they stop?

"...it had to do with gravity..."

I suppose that everything has to do with gravity to a greater or lesser degree. It's a heavy topic. But gravity plays no special role in this brainteaser other than keep the railroad cars on the face of the Earth.

"...friend Slugger works up north in the locomotive sheds setting wheel alignment. He uses a real BFH..."

With a name like Slugger, what else would he use and what else would you expect?

"...sort of like the same reason that motorcycles only tip over when they stop?"

Motorcycles tip over when they stop because the driver cannot make the tiny corrections needed to keep the machine upright. That's similar to why airplanes fall outta the air when they stop moving.

No, the answer to this question is much more in the realm of mechanical engineering, is very logical, and once (properly) explained is easily understood. It's not obvious, however, 'til it's made obvious.

When you're ready, I can give you at least two very important factoids. Here's number zero: The flanges have nothing to do with it.

Speaking of flanges, do you know what part of the train is always going backwards?

(Gee, lemme think for a second......)

"what part of the train is always going backwards"...hmmm That would be the brakeman's paycheck. Goes backwards regardless of which way the train moves. Goes backwards faster if the train is standing still, and, speaking of stills, goes backwards in direct proportion to the rate of increase in the cost of liquor. How's that for stereo-typing? And yes, I am using both hands.

Still having a hard time with the idea that flanges don't have anything to do with turning corners. I suppose that an object in motion tends to go in a straight line. Like a bullet, or my wife at the sale table at Filene's, but there must be more to it. Wouldn't the flanges be needed to compensate for the correolis effect? (got the wrong dictionary).

I've got it! Isn't that what the engineer does?

"...what part of the train is always going backwards..."

Ok, ok. I asked this question with a lead-in like, "Speaking of flanges..." so I just assumed that you'd get the picture that something about the flanges always goes in the opposite direction to the train.

Because the axle is moving with the train and at the same velocity, and because the wheel is in direct contact with the rail and not moving, the outermost edge of the flange (which extends BELOW the contact point of the wheel with the rail) moves opposite to the train's direction. It's simple geometry.

Because the trainman's union cannot control this backward motion of the flange, it compensates by insuring the forward motion of employees' paychecks. Always.

Flanges have nothing to do with keeping the train on the rails while it is underway. (If they did, they'd be worn down in no time and your ears would be dead from all the screeching and grinding -- sorta like riding the "T" under Boston...) Flanges keep the train on the rails when it's sitting still. Thus, this magic process I'm teasing you about is a dynamic process.

Let me ask you this: How does your car negotiate the bends in the road? No rocket science here, just a common-sense answer......

You may be suggesting that the load carrying surfaces of the rails are slightly canted towards each other. I suppose that if toe in is not possible, as in the case of a train, the next best thing would be to simulate the effect in the rails. Am I on the right track? Do I need to switch my thinking at some point?

It had occurred to me that because the engines always turn at the same speed no matter whether the train moves or not, that this would prevent torque from tipping the train over when it starts up, but that's too easy.

"...surfaces of the rails are slightly canted towards each other..."

They might or might not ne, but it's not related to the question at hand.

"...toe in is not possible, as in the case of a train, the next best thing would be to simulate the effect in the rails..."

Toe-in is not part of the equation. However, the thought DOES lead to clue number 1:

The two wheels on an axle are rigidly, solidly tied to the axle. The wheels are NOT independant.

"Am I on the right track? Do I need to switch my thinking at some point?"

Not really, and probably.

"...the engines always turn at the same speed no matter whether the train moves or not, that this would prevent torque from tipping the train over..."

The torque reaction sustained by the vehicle is not related to the engine's speed. It is singularly related to the torque delivered to the drive system. Obviously, a slow engine is less able to produce mind-shattering or car-flipping torque, but that issue is aside from your thesis.

Ready for clue number 2?

By the way, do some research on Richard Feynman. This was one of his brain teasers for his physics students. The answer boils down to simple mechanics.

Wishing for an earthquake...

Not really, but do tell, Don. Please.

Why does a train stay on the tracks?

Read the original question. He asked how they stayed centered on the rails. Gravity keeps them ON the rails. Toe-in is also a clue, but where?

BTW, locomotives are diesel-electric. The engine turns an alternator converting the rotating power to electrical power which is piped to traction motors. They used to be exclusivly DC but are now AC. A chopper circuit is used with BF'n semiconductors to convert the DC electrical power to AC. Speed sensing circuitry keeps the motors at peak efficiency and doesn't allow for wheel slippage. RUN 8 all the time!

What you want, when you want it. AMEN!

OK, later. I gotta prepare the 3D freebody force vector diagrams and differential equations so you'll understand.

Geez, and I thought this was soooooo easy, too.....

It is, NMRA RP-25 comes to mind.

"It is, NMRA RP-25 comes to mind."

Could you please elaborate on that?

You better simplify them differential equations pretty good. I have lots of trouble fingering out final drive ratios...

Or, just after it gets pushed, yell, "NO WAIT!"

More like "Guess we won't try that again."

A very interesting and erudite discussion between Napolean and Don but I wish to register a complaint! I have worn out my mouse, modem, and lost my beauty sleep following this lot!

What has all this got to do with the price of fish anyway??????

Colin.

You didn't need the beauty sleep anyway. If you don't believe me, go buy a fish, take it downtown, and see which of you gets a date first.

That's why I enjoy this board so much! Not only have I learned a lot 'bout my "Velma"(86 744 Gle) and how to keep her running forever but I also picked up lot of wisdom from the volvo gurus that resides here!!Thank ya'll!!!

Reysc( getting ready to install used starter and may the volvo gods smile on this DIYer)

I think that usually indicates a fault code in the climate control. Check the FAQ, there may be some articles there on extracting the codes from that year/model.