Does the outside temperature effect traction?
Modeling the "Fargo Area Rapid Transit" in O scale 3 rail.
If there is moisture on the rail head and the ambiant temperature is dropping, yes. I don't remember the co-efficient of friction changing with temp from physics many years ago. Maybe others with more practical experience will have a definitive answer.
the biggest problem with cold weather is that the metal gets brittle and its easier to tear a train up, so you handle it easier, other wise ive never known it to be a problem. or noticed any differance.
Temperature does not have a significant effect on traction. However, it has a significant effect on being able to maintain air pressure in the trainline, as colder temperatures promote leakage as all the air hose gaskets get harder and shrink in the cold. The inability to keep air pumped up on the trainline can thereby cause brakes to apply throughout the train if the trainline pressure cannot be maintained at the proper level. Trains with brakes on pull much harder than trains with all brakes released.
Trains with brakes applied can create flat spots, significant flat spots, on wheels. Cold flat spotted wheels hammering on cold rail can create either broken wheels or broken rails as cold steel is more brittle than warmer steel.
Never too old to have a happy childhood!
Boyd Does the outside temperature effect traction?
Yes - though typically not so much as the other factors mentioned by other posts above.
Note that what you're asking about is the coefficient of static friction = the surfaces not quite sliding past each other, such as the driving wheel on the rail - as opposed to the coefficient of rolling friction = resistance of the wheels rolling on the rails, which is much less.
Here's the abstract from a 1941 report by the London Midland and Scottish Rwy. Co., which provides some data on the point. But without being able to review the entire report, I am not confident in saying whether the coefficient of friction increases or decreases with temperature increases - though I suspect it would be the increase.
Robert Schnurmann 1941 Proc. Phys. Soc. 53 538-546 doi: 10.1088/0959-5309/53/5/305
Robert SchnurmannLondon Midland and Scottish Railway Company, Research Laboratory, Derby
Abstract. Angles of repose of metals have been measured under controlled vacuum conditions.
Preliminary measurements were made at room temperature in air. As it was found that vibrations tended to reduce the angle of repose, they were eliminated. Naked metal surfaces were obtained for aluminium and cadmium by cleaning by volatilization in a high vacuum. Interesting results were found with a steel slider when a deposit of volatilized aluminium had formed on steel crutches.
Experiments on cadmium cleaned by volatilization at various temperatures at which the whole friction chamber was baked out were carried out in the range from + 176° C. to -100° C. The results, in spite of the inevitable fluctuations of individual values at any particular temperature, clearly show a general drift with temperature, and are a first instalment towards an approach to the thermodynamical criterion for the fundamental mechanism of friction between naked metal surfaces. A conservative analysis of the results of measurements between -100° C. and + 100° C. leads to a temperature coefficient of the angle of repose dα/dt=-3.5 × 10-2 degrees, while a bolder interpolation would raise this numerical value by a factor of about two (dα/dt=-8 × 10-2 degrees). Above about + 100° C, the angle of repose of naked cadmium increased with rising temperature.
Print publication: Issue 5 (1 September 1941)Received 7 April 1941
- Paul North.
Paul_D_North_Jr Boyd Does the outside temperature effect traction? Yes - though typically not so much as the other factors mentioned by other posts above. Note that what you're asking about is the coefficient of static friction = the surfaces not quite sliding past each other, such as the driving wheel on the rail - as opposed to the coefficient of rolling friction = resistance of the wheels rolling on the rails, which is much less. Here's the abstract from a 1941 report by the London Midland and Scottish Rwy. Co., which provides some data on the point. But without being able to review the entire report, I am not confident in saying whether the coefficient of friction increases or decreases with temperature increases - though I suspect it would be the increase. Experiments on the temperature coefficient of static friction Robert Schnurmann 1941 Proc. Phys. Soc. 53 538-546 doi: 10.1088/0959-5309/53/5/305 Robert SchnurmannLondon Midland and Scottish Railway Company, Research Laboratory, Derby Abstract. Angles of repose of metals have been measured under controlled vacuum conditions. Preliminary measurements were made at room temperature in air. As it was found that vibrations tended to reduce the angle of repose, they were eliminated. Naked metal surfaces were obtained for aluminium and cadmium by cleaning by volatilization in a high vacuum. Interesting results were found with a steel slider when a deposit of volatilized aluminium had formed on steel crutches. Experiments on cadmium cleaned by volatilization at various temperatures at which the whole friction chamber was baked out were carried out in the range from + 176° C. to -100° C. The results, in spite of the inevitable fluctuations of individual values at any particular temperature, clearly show a general drift with temperature, and are a first instalment towards an approach to the thermodynamical criterion for the fundamental mechanism of friction between naked metal surfaces. A conservative analysis of the results of measurements between -100° C. and + 100° C. leads to a temperature coefficient of the angle of repose dα/dt=-3.5 × 10-2 degrees, while a bolder interpolation would raise this numerical value by a factor of about two (dα/dt=-8 × 10-2 degrees). Above about + 100° C, the angle of repose of naked cadmium increased with rising temperature. Print publication: Issue 5 (1 September 1941)Received 7 April 1941 From: http://www.iop.org/EJ/abstract/0959-5309/53/5/305 - Paul North.
So Paul exsplain to me the differance in how my train handeling should be in starting or stopping my train at 60deg then say 95 deg and then 10deg. what is the things i should watch for.in both starting and stopping. With the slack bunched or strecthed. starting from a stop going up hill or taking off at the bottom of a hill.
wabash1 So Paul exsplain to me the differance in how my train handeling should be in starting or stopping my train at 60deg then say 95 deg and then 10deg. what is the things i should watch for.in both starting and stopping. With the slack bunched or strecthed. starting from a stop going up hill or taking off at the bottom of a hill.
I'm not going to bother reading the report, since even the abstract is beyond my level in that realm.
I suspect that steel on steel, sans external factors (moisture, lubricants - natural and man-made, sand) will keep a rather narrow range of "stickiness" throughout the range of temperatures we normally see.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
LOL Well this is traction of bare rail or at least that was the impression i was under. so NO Sand.
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