# Need help finding coefficient of rolling friction of UHMW (close to Teflon) on Steel

Does anybody have a table of rolling friction coefficients? I can't find the one I'm looking for. I have a vertical door opening (similar to a garage door) where there are UHMW polymer rollers rolling in a track. I read somewhere that the coeff of rolling frict would be close to teflon on steel... but I can't find that either.

Any help would be appreciated.

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rcgldr
Homework Helper
Don't forget the rolling friction of the bearing surfaces inside those wheels. Even if you could get "ideal" rolling friction numbers for those materials, there's still the issue of friction as the sides of the wheels rub on the tracks. Seems like the only solution would be to measure the force needed move the door, but this would require a long horizontal run, or some tricky math to deal with the door transitioning from horizontal to vertical.

ah ha... it doesn't go horizontal like a garage door. It is a 3-leaf door, and the leafs simply roll straight up and out of the way. Analogy would be a guillatean (or however you spell that!). straight up & straight down, usually near perfect counterweight. All 3 leafs retract up and are stored above the doorway, still totally vertical.

rolling resistance coefficient of aluminun on lawn

I am looking for the rolling resistance coefficient of aluminum on lawn, I assume I won't find this in a table?
I was wondering whether there are there other ways to find this coefficient, other than making an aluminum wheel and rolling it down a slope?

That's a damn hard question because the surface of lawn is nonhomogenous. So the coefficient will change depending on where on the lawn you do it. Your best bet would be to do it many times at many locations and average it.

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I am looking for the rolling resistance coefficient of aluminum on lawn, I assume I won't find this in a table?
I was wondering whether there are there other ways to find this coefficient, other than making an aluminum wheel and rolling it down a slope?
Actually that's quite well studied (by prople who design golf course greens).
Try googling friction on grass.

This site has a lot of good info on the subject.http://www.oxfordcroquet.com/tech/lawnspeed/index.asp" [Broken]

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Isn’t friction different from rolling resistance or is it common practice to mix these terms?
Also, those calculations happened without taking the radius into account as the radius of their ball is constant.

Hello guys,

I have a similar problem with project I’m involved with. I’m not an engineer; rather I’m a welder fabricator. I built 2 set of dollies to carry our units (Skid) from shop to yard for painting purpose. Each dolly is 3’ X 12’ with 4 steel 6 5/8” diameter which is rolling on 2” wide steel track and the span between wheels is 10’. Both 2 dollies supposed to carry up to 50 ton skid from shop to yard. Normally we use a big forklift to push the dollies to the yard, but that is somehow trouble since we can’t always focus the force on the dolly being pushed so we decided to set up and electric or hydraulic winch to do the job. I need to know how much force it needs to roll the 50 ton unit on the track so I can select a correct winch capacity. It would be great if someone could give me an idea. Thank you very much.