Coefficient of Friction for cable pulling calculations

[kenaslan]

The Southwire pulling software has the COF at 1.5 for a cable tray pull. This is fine if one is using new perfectly maintained rollers. But in the real world, rollers are rusty, not maintained, bent, dirty, ect. I am thinking of using a COF of 2.0, does anyone have any thought on this?

Thanks

 

[junkhound]

thinking of using a COF of 2.0, does anyone have any thought on this?

If you find that is true, apply for a patent, I want some of that there COF 2.0 stuff for my tires!

				COF
Rubber	Wet Asphalt	Clean and Dry		0.25 - 0.75
Rubber	Dry Concrete	Clean and Dry		0.6 - 0.85
Rubber	Wet Concrete	Clean and Dry		0.45 - 0.75

 

[kenaslan]

2.0 is worse than 1.5
Any idea on Tension Adder for type TC-ER. I use 200 per IEEE 576-2000 (10.3.5) for MC-HL

 

[junkhound]

No idea what the southwire pulling software is, too lazy to search for it.

Since this is an 'engineering' tab, replied for simple COF physics since no one else had responded.

If there are no surfaces so rough that there is mechanical interlock (which no longer is friction), then the 1.5 is about max COF and occurs when simiar materials are in close contact. For instance, nylon wires against other nylon, the static friction can be close to 1.5 due to Van der Walls forces if the nylon has been sitting against other nylon in warm temperatures. (or poly against poly, etc)