Where can I find data to approximate coef of friction?

[loquillo]

I'm modeling a safety brake for an elevator and is kind of difficult to measure the coefficient in such a thight area. The rail contains brown rust and the approximate load applied by the brakes would be 10,000 lbs. I have search a couple of approximations but I don't know how much does the rust affect the friction coef.

 

[CoryPad]

A safety-related item like this must have experimental determination of friction coefficient. This property varies so much that using data derived from other applications (with different environmental conditions, materials properties, etc.) is not suitable.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[notnats]

Is the rust likely to get polished off once the elevator is in service? If so it would be more conservative to measure coeff of friction on a polished rail.

Jeff

 

[loquillo]

No, the rail does not get polished at all.

 

[zekeman]

Why don't you assume the polished condition anyway to give you a conservative answer, since it is obvious that the rusted state would have a greater coefficient?

 

[monkeydog]

What makes you think a rusted state would give a higher coefficient? Wouldn't the rust sluff off and act as a dry film lubricant?

 

[Pekelder]

Rust forms most of the time under influence of moisture. Wet, rusted steel can ben very 'slippery'under load, since the water is retained by the rust. Steel is liable to have condensation on the surface. I agree with CoryPad, try to test it!

Regards,
Pekelder