'adhesion' is..

[Anonymous]

QUOTE: Mookie said:


Martha Stewart - it is a good thing!

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)]

[Anonymous]

QUOTE: Mookie said:


Martha Stewart - it is a good thing!

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)]

[zardoz]

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 fastest, next is the wheels, then the rail.

[zardoz]

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 fastest, next is the wheels, then the rail.

[wabash1]

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.

[wabash1]

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.

[mudchicken]

Ed:

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)

[mudchicken]

Ed:

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)

[Mookie]

Wow - you guys are really throwing a lot at me!

Let's start backwards - from serious to funny -

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!

Mookie

[Mookie]

Wow - you guys are really throwing a lot at me!

Let's start backwards - from serious to funny -

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!

Mookie

[Anonymous]

QUOTE: Originally posted by cabforward

QUOTE: Originally posted by Alaskaman

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.

>> yes, it does. a wheel slips when the load is too heavy, or the engine is too lite..

adding more weight to locomotive wiil help reduce adhesion. That's why cement is added to slugs -to improve adhesion.

>> i don't follow this.. if a wheel slip is due to loss of adhesion, how will a heavier loco reduce it further? doesn't heavier engine = greater adhesion?

>> the next comment makes sense.. cement is added make the loco heavier to increase adhesion..

I think i kinda messed up here. You're right. Thats what i meant to say. Thank you, i was kinda sleepy when i wrote it....[|)][|)][|)]

[Anonymous]

QUOTE: Originally posted by cabforward

QUOTE: Originally posted by Alaskaman

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.

>> yes, it does. a wheel slips when the load is too heavy, or the engine is too lite..

adding more weight to locomotive wiil help reduce adhesion. That's why cement is added to slugs -to improve adhesion.

>> i don't follow this.. if a wheel slip is due to loss of adhesion, how will a heavier loco reduce it further? doesn't heavier engine = greater adhesion?

>> the next comment makes sense.. cement is added make the loco heavier to increase adhesion..

I think i kinda messed up here. You're right. Thats what i meant to say. Thank you, i was kinda sleepy when i wrote it....[|)][|)][|)]

[Anonymous]

QUOTE: Originally posted by railpac

QUOTE: Mookie said:


Martha Stewart - it is a good thing!

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)]

Leave Martha alone.... She's into enough trouble already.

[Anonymous]

QUOTE: Originally posted by railpac

QUOTE: Mookie said:


Martha Stewart - it is a good thing!

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)]

Leave Martha alone.... She's into enough trouble already.

[edblysard]

Yes, some are more "fair" game than others, but "zero tolerance" means zero for everybody, or at least it should.
Leading by example was what I was taught, with a Chief Petty Officer for a dad, it was drummed into this thick head that you never ask someone else to do something you wouldnt or couldnt do yourself first, and if you expected a certain type of behaviour, then you had to behave in a like manner.
But it is scary how, at a certain level of management, some of the safety rules seem to not be applied as stringently.
Stay Frosty,
Ed

QUOTE: Originally posted by mudchicken

Ed:

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)

[edblysard]

Yes, some are more "fair" game than others, but "zero tolerance" means zero for everybody, or at least it should.
Leading by example was what I was taught, with a Chief Petty Officer for a dad, it was drummed into this thick head that you never ask someone else to do something you wouldnt or couldnt do yourself first, and if you expected a certain type of behaviour, then you had to behave in a like manner.
But it is scary how, at a certain level of management, some of the safety rules seem to not be applied as stringently.
Stay Frosty,
Ed

QUOTE: Originally posted by mudchicken

Ed:

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)

[PNWRMNM]

Mookie,

Adhestion is the scientific way of measuring how "sticky" two surfaces are. Pick any two. Rubber on pavement is very sticky, has a high adhesion. That is why cars dont usually spin out on dry pavement. Wet pavement has less adhesion, is more slippery, longer stopping diatance, more likely to spin out. Ice has even less adhesion, that is why you have to walk carefully.

In rail context the only thing that counts is weight, on powerd axle, and adhesion, expressed as a ratio. You are interested in tractive effort, the power to pull a train. For dry rail and DC motors is about 25%. Most locomotives are about 65,000 pounds per axle. If you have a four axle loco the most pull you will get is about 65,000 pounds (4axles * 25% * 65,000#axle loading). For an SD unit figure about 97,000 pounds. If you are building trains and power consists is wise to give yourself a bit of fudge factor, so figure 60,000 and 90,000 pounds respectively.

How much train for how much power depends on the Davis equation which is more complicated than adhesion. The above is for drag freight. If you are running intermodal trains it is more convenient to talk in Horsepower per Ton. Typical range would be 3-4 HPPT. In this service horsepower converts to speed. Note that this approach cares noting about weight of locomotives or how many axles. All that counts is horsepower. That is why the ideal intermodal unit is 4 axles. You dont have to drag all that extra weight around and lift it up and down all the hills, burning fuel in the process.

The reason there are so few high horsepower GP units around is fleet flexibility. You can go back and forth between drag freight and intermodal with SD units with much less performance penalty than you can with GP units.

Did that help??

Mac

[PNWRMNM]

Mookie,

Adhestion is the scientific way of measuring how "sticky" two surfaces are. Pick any two. Rubber on pavement is very sticky, has a high adhesion. That is why cars dont usually spin out on dry pavement. Wet pavement has less adhesion, is more slippery, longer stopping diatance, more likely to spin out. Ice has even less adhesion, that is why you have to walk carefully.

In rail context the only thing that counts is weight, on powerd axle, and adhesion, expressed as a ratio. You are interested in tractive effort, the power to pull a train. For dry rail and DC motors is about 25%. Most locomotives are about 65,000 pounds per axle. If you have a four axle loco the most pull you will get is about 65,000 pounds (4axles * 25% * 65,000#axle loading). For an SD unit figure about 97,000 pounds. If you are building trains and power consists is wise to give yourself a bit of fudge factor, so figure 60,000 and 90,000 pounds respectively.

How much train for how much power depends on the Davis equation which is more complicated than adhesion. The above is for drag freight. If you are running intermodal trains it is more convenient to talk in Horsepower per Ton. Typical range would be 3-4 HPPT. In this service horsepower converts to speed. Note that this approach cares noting about weight of locomotives or how many axles. All that counts is horsepower. That is why the ideal intermodal unit is 4 axles. You dont have to drag all that extra weight around and lift it up and down all the hills, burning fuel in the process.

The reason there are so few high horsepower GP units around is fleet flexibility. You can go back and forth between drag freight and intermodal with SD units with much less performance penalty than you can with GP units.

Did that help??

Mac

[kenneo]

QUOTE: Originally posted by zardoz1

Mookie-
My view of adhesion ... 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.

===============================================================
from WABASH1 Posted: 29 Aug 2003, 11:55:54 AM
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.
================================================================
Perhaps you remember the incident a few years back where the SP turned over a tank of RoundUp into the Sacramento River and it killed everything in the river? Well, the above is what happened, except no knuckle. Train was wrapped around a very tight curve (as in U-Turn type)(about 10 degree) on a bridge over the river. Second unit slipped and lost its feet, dropped its load, then got its feet back and rolled the head 10 cars on their sides, one of which was our tank car which dropped into the river and split open. This train was heavier than the "rules" allowed and so was operating at less than minimum continuous speed. In addition, the head 8 cars were empties and the first load was the tank.

[kenneo]

QUOTE: Originally posted by zardoz1

Mookie-
My view of adhesion ... 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.

===============================================================
from WABASH1 Posted: 29 Aug 2003, 11:55:54 AM
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.
================================================================
Perhaps you remember the incident a few years back where the SP turned over a tank of RoundUp into the Sacramento River and it killed everything in the river? Well, the above is what happened, except no knuckle. Train was wrapped around a very tight curve (as in U-Turn type)(about 10 degree) on a bridge over the river. Second unit slipped and lost its feet, dropped its load, then got its feet back and rolled the head 10 cars on their sides, one of which was our tank car which dropped into the river and split open. This train was heavier than the "rules" allowed and so was operating at less than minimum continuous speed. In addition, the head 8 cars were empties and the first load was the tank.

[edblysard]

Adhesion is the kind of tape that wrapped around my head from where my wife knocked the crap out of me because I made a joke about my cousin in california earlier today...[:D]
Ed

[edblysard]

Adhesion is the kind of tape that wrapped around my head from where my wife knocked the crap out of me because I made a joke about my cousin in california earlier today...[:D]
Ed

[Modelcar]

....Ed, I read something you wrote earlier and I wondered about...Something along the lines you said you got in trouble for...and required that special Adhesion tape. I kinda chuckled a bit when I read your account of that today.

[Modelcar]

....Ed, I read something you wrote earlier and I wondered about...Something along the lines you said you got in trouble for...and required that special Adhesion tape. I kinda chuckled a bit when I read your account of that today.

[zardoz]

Wabash-

The new units monitor wheel slip via minute fluctuations in current variances to the wheels. There is no way any engineer can respond with the minute adjustments the loco make many times per second. The new locos may take some the fun and creativity out of being an engineer, but they are more efficient.

[zardoz]

Wabash-

The new units monitor wheel slip via minute fluctuations in current variances to the wheels. There is no way any engineer can respond with the minute adjustments the loco make many times per second. The new locos may take some the fun and creativity out of being an engineer, but they are more efficient.

[joseph2]

Sand.And sanders that work.

[joseph2]

Sand.And sanders that work.

[Anonymous]

QUOTE: Originally posted by edblysard

Adhesion is the kind of tape that wrapped around my head from where my wife knocked the crap out of me because I made a joke about my cousin in california earlier today...[:D]
Ed

Gee, I guess that means you had your bell rung. [;)]

http://www.trains.com/community/forum/topic.asp?page=6&TOPIC_ID=6646

[Anonymous]

QUOTE: Originally posted by edblysard

Adhesion is the kind of tape that wrapped around my head from where my wife knocked the crap out of me because I made a joke about my cousin in california earlier today...[:D]
Ed

Gee, I guess that means you had your bell rung. [;)]

http://www.trains.com/community/forum/topic.asp?page=6&TOPIC_ID=6646