who understands the adhesion of a loco to the railhead? the trains glossary says it is how well the loco grips the rail… if a loco is designed correctly, does this change over time? if a rail is worn or has other problems, adhesion would change… does adhesion change for keeps or can it ‘come and go’?
industrial discussions are technical and mostly math formulas and physics of substances…
is a slipping wheel a sign of loss of adhesion?
besides the wheel, the weight on traction axles and the railhead, are there other aspects of adhesion to be considered (that can be understood by non-geniuses)?
All I know is that when “adhesion,” is lost and regained rapidly, I lose butt to seat adhesion and have to go back and pack iron and put my train back togeather. Adhesion good! Slippage bad!
Ken
Wheel starts to slip when power applied to it is greater than it can pull or the wheel spins faster than the speed of train (does this make sense?)
That’s loss of adhesion. In modern locos when wheelslip is detected, sand is applied automatically and power is reduced. Wheelslip usually is caused by wet rails (ice, rain, snow) or grade. but adding more weight to locomotive wiil help reduce adhesion. That’s why cement is added to slugs -to improve adhesion.
I hope i did some good here.
Your cousins out here in hi-rails tend to go nowhere fast when it rains and they don’t have the luxury of sand (as we watch the tachometer climb into the red zone)…
Hey mudchicken, on a side note, we just had a roadmaster get sent home and had to pee and blow. Seems that he copied track and time wrong, problem being that he was hauling some brass around when he did this. One of the heave duty officials asked to see his T&T and woops, went outta the limits. Bye bye! Bummer for him, he was a cool dude. Bad gig. On coming trains are unforgiving as you know.
One of my worst fears is to hear the infamous, “secure your train, the trainmaster will be there to talk to you soon with your relief crew!” from the dispatcher.
Ken
French or Latin; French adhésion, from Latin adhaesion- Date: 1624
steady or firm attachment
OR
the action or state of
OR
the abnormal union of separate tissue surfaces by new fibrous tissue resulting from an inflammatory process
OR
the molecular attraction exerted between the surfaces of bodies in contact
That is Adhesion.
If you have any other questions, like above … please feel free to contact your local dictionary, or you may pick up a copy for yourself at a bookstore, grocerystore and many other local retailers.
I think every engineer would love to have good adhesion all the time[:D]. But unfortunately ya can’t[:(!]. Basicly if you are going up a hill, or running in ice, snow, rain, or any precipitation you won’t have good track adhesion.
PRACTICAL DEFINTION IS THE RATIO OF DRAWBAR PULL IN POUNDS TO LOCOMOTIVE WEIGHT. IF 250,000# UNIT PULLS 50,000 # RATIO IS 50/250 OR 20%. ADHESION ACTUALLY OCCURS WHERE THE WHEEL MEETS THE RAIL, AND IT IS A PHYSICS PROBLEM. SIMPLEST WAY TO SEE WHAT IT IS FOR A PARTICULAR UNIT IS TAKE PULL AT MINIMUM CONTINUOUS SPEED, WHICH IS LIMITED BY ADHESION AND DIVIDE BY WEIGHT AS ABOVE.
ADHESION IS VERY SENSATIVE TO ENVIRONMENTAL FACTORS. DRY RAIL IS ABOUT 25%. WET RAIL 17%. SAND ADDS 8%, SO SAND ON WET RAIL IS ABOUT EQUAL TO DRY RAIL. THESE FIGURES FOR DC TRACTION MOTORS. AC TRACTION MOTORS RATED AT 33%, PRESUMABLY ON DRY RAIL.
MORE WEIGHT DOES NOT GIVE MORE ADHESION, IT GIVES MORE PULL WITH WHATEVER ADHESION IS.
What? [?] See this is what I have been trying to figure out for the past 6 mos. Still don’t get it - but then physics wasn’t my best subject. And the dictionary didn’t help!
Roadmaster was tested for alcohol/drugs. He had some top officials on board the train. One of the top officials asked to see his (some body part) (test results)(time and temperature) and he was over the limit of whatever they looked at. He was fired probably permanently. He was one of the good guys. It is a bad thing. He was obviously where he shouldn’t have been and could have had an accident with another train. The rest is in English.
ever been on wet rails with a locomotive that has the wheel slip circuit disabled. too see a shower of sparks spewing from all 6 axles when its dark is quite a spectacle
Mookie,
In plain english, the roadmaster copied his track and time incorrectly. T&T gives you permission to occupy a partcular section of tack between two given points or milepost, for a specific period of time.
He copied it incorrectly, and was outside the limits he was given premission to occupy.
Any opposing traffic could hit him.
Doing this knocks a rung or two out of the ladder to success!
The fact they made him do a drug test, and sent him home indicates they had a pretty good gripe with him, its rare for officals to rat each other out, unless there is a power struggle going on.
You have a copy of the UPs track and time warrant, it was tucked in the side of the folder I sent you.
Look it over, it will make sense quickly.
Stay Frosty,
Ed
I don’t know Mook, personally I think she’s kinda scary. I mean she can cook AND garden. Personally I don’t know ANYBODY who can cook AND garden. [;)][B)]
Mookie-
My view of adhesion is how much ‘traction’ a (in this case) locomotive’s driving wheel(s) can get on the rail. Understanding that the actual contact area of a train wheel on rail is approximately the area of a dime, it might be easier to understand how a locomotive might lose contact with the rail. Just as with the tires on your vehicle, any material that comes between the driving wheel and the road (rail) will cause a loss of traction, which translates as loss of adhesion. Other things not listed above which limit rail traction are leaves (during fall season), and oil dripped from cars on crossings.
The new, fancy locomotives have automatic systems that detect slippage far faster than an engineer could, and apply sand only in the amount needed. In the (good?) old days, we had to apply sand manually, jockey the throttle constantly to try to get the most traction before the wheels started to spin; when they did spin, it took a few seconds for the wheel to stop spinning and slow enough to regain traction. And when it grabbed, you could really feel it. If too many wheels would spin and then regain traction at the same time, it could be enough to cause a slack run-in-and-out which could result in a knuckle or drawbar failure. Too much sand could actually cause the train to slow a bit due to additional friction. And when you’re trying desparately to keep your train from stalling on a hill, going literally 1 mph, a little slow down could be just enough to cause the stall.
And if the roadmaster ever saw geniusorus spinning wheels like he described, I’m sure a report would be made; spinning wheels can quickly grind down a rail head and cause the rail to fail (at worst) or at least cause the rail to need replacing (doesn’t do the loco much good, either).
BTW, did you know that for maintenance purposes, the metal used in the rails, wheels, and brake shoes are of different composition so wear will occur at the least expensive location. The brake shoes wear the fa
newer engines cant regulate a spinning wheel better than a engineer can. i can here the engine change sound from the way it was pulling and know its trying to slip. drop a notch and go then get my notch back. the new engines drop the load all together then load back up. this couse loss of speed and run in. as train runs in the power starts going back to the rail the train starts running out. then you get a knuckle. if the engineer is in charge he drops a notch a few cars on the rear will take slack slow and then go out smooth dropping one notch wont tear a train up. your still pulling… things that will cause wheel slop. wet rail, grease ( melted snow will but not snow by its self. or ice ) wet leaves are the worse. you cant get going or stop with these slick things on the rails.
In a “zero tollerance” environment, everybody is fair game (some more than others)…What continues to frighten me is operating supervisors (TM, Rd4menn, Supt.s etc.) out there in hi-rails zooming by at 60mph…by all rights they should be in the ditch. Even though there is no GCOR rule against it, most high rail gear makers print in large letters that the gear is good for 35mph or less (there isn’t much of a flange holding them in line with the rails)
Adhesion in that respect I understand. It is the drawbar pull and engine weight, percentages, how many engines, how much weight, figuring an Einstein computation - it is just all too much for my pea-brain!
Ed - I will check again when I get home tonite. I looked at it, but now that I have something to remember, I will look again.
John - I know what you mean - I try not to do either! But in all seriousness, if you watch her and then watch the rest of the cooks/chefs/can openers on the Food Network - she is the quietest one of all. She doesn’t throw her hands in the air, the chicken doesn’t get bammed and she speaks rather quietly. Kind of like a mother telling her child a bedtime story. I am just mesmerized by her slow movements and quietness, for 5 min, before I am sound asleep!