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Topic Date User

Cams Ripping At Arapiles - common? 15-Oct-2009 At 1:59:22 PM cruze

Message

On 15/10/2009 One Day Hero wrote:
>On 14/10/2009 Richard wrote:
>>What theory where? To back up this claim you need to demonstrate that
>>the force you can apply with one hand is similar to the force of your
>entire
>>body weight with a realistic fall factor.
>
>????
>
>Right, I think we now have evidence that Patto gets the cam thing more
>than Richard who gets it more than Afj.........by the way, how did you
>come up with your coefficient of friction numbers Richard? I'm a bit suss
>about your stuff now

A bit of simplified force analysis will provide that to prevent slipping:
[coefficient of friction] >= tan(contact angle)

Regarding the tug test, while it is true that for a given contact angle the force applied perpendicular to the rock will increase in direct proportion to the force applied along the axis, I would say that the greatest benefit in tugging gear is to provide peace of mind enough to get you through to the next piece without faling at all! Other than that there probably would be some merit in tugging to break off loose surface crystals that could reduce the coefficient of friction of the rock surface during a fall. After all rock failure is probably a lot more likely than gear failure in most cases, esp soft sandstone.