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Petzl Pro Traxion Good all round Pulley Choice?

Mr Poopypants

16-Oct-2011
10:05:19 PM

G'day again, Lee & Co.

I've used them on both statics and dynamics and I know what you mean, Lee. Despite the logic of dynamic absorbing energy I always feel more comfortable on the static, as it doesn't stretch as much. Less edge rubbing, acceleration etc. Just need to make sure it takes up and you don't shock load the static. (I use a Torse and tie the traxion to it upright with a shoelace)

I re-checked Petzl's website and the rating for such use is 4-6.5kn for sheath breakage, which is the real issue with camming ascenders, they rip through the rope and cut it.

The interesting thing is that the static and dynamic are rated to virtually the same loads, indicating that the cam can only take so much force before it cuts the rope. I still feel better with the static, got to say. Less movement.

The Pro is a no-go for self-belays. There have been accidents in Nth America where the rope dislodged off the cam into the side plate and was severed, leading to death. Comes up if you google self-belays with traxions. Pretty well reported and seems reliable. Petzl don't recommend the Pro for self-belay.

Gotta say I love the mini-traxion. Saves the embarrassment of having a belayer.

Guess I'll continue to use what I can and yelp occasionally, which is nothing new! :-)

Cheers

G.

patto

16-Oct-2011
11:46:27 PM

On 16/10/2011 Rocker wrote:
>Patto, could you please clarify?
>
>On 16/10/2011 patto wrote:
>>
>>A quick calculation shows that your assumption is incorrect
>
>F=MxA
>
>>If you assume ZERO SLACK in the rope then the subsequent peak force is
>>2x body weight regardless of the elasticity of the rope. Thus the force
>>on static and dynamic ropes is the same.
>
>F= 80kg (800nm) climber x 0 Acceleration
>Therefore the force (or weight) on the rope is 80kg, how can it be 2x?
>Yes, in this instance there would be no difference between ropes.
>

Even if there is no slack there is still acceleration if the climber slumps onto the rope. The rope is at 0 tension and needs to reach mg tension. The climber will still drop as the rope stretches. It turns out that the peak force during this event is always 2x, whether it is a static rope, dynamic rope or steel cable. If the climber very 'gently' transferred his weight to the rope then the weight then the peak force is approximately the climbers weight.

The rope will stretch absorbing energy equal to E=0.5hF (where h is total distance and F is final and peak force). Total energy being absorbed is E=mgh. Thus mgh=0.5hF >>> F=2mg.

ademmert

17-Oct-2011
12:50:44 AM

On 16/10/2011 Lee C wrote:

>Additionally probably the biggest problem with toothed devices is that
>when they "fail' it is in fact the rope sheath that fails (first) and a
>static sheath is vastly better in that regard.

I think this is the main point for.self belay . Teeth = bad. self belay on either static [preferred ] or dynamic get a device without teeth!!

Jayford4321

17-Oct-2011
1:00:06 AM

On 16/10/2011 andesite wrote:
>On 16/10/2011 jammin wrote:
>>the lucky binder was rated to 2.5 ton, the climber was a lightweight.
>
>shouldn't that be 'rated to 25kN' ;-) or was this biner specifically designed
>for 'static' loads?

It was rated at 25 Kn but as you have just demonstrated most climbers don't understand that 1 Kn is equal to 100 Kg,
and so the force/energy of Kg's when they are falling and gathering inertia and therefore extra mass, is converted to Kn's to give a kinetic expression.

Lee says he "feels" that the dynamic rope is worse than the static,
well he is falling less distance on a static or low stretch rope but the peak loading is much higher.
whereas with the dynamic rope he will fall further but the peak loading will be less.
all this is really a mute point tho as the traction should not be used in this way!
get an ICS rope grab, identical to a rescue scender but better, personally I use a tricked out Gri Gri
perfect for working a route by my self, if I need to jug up its already half the ascending system in place
and if I have a fixed rope it runs very smoothly, if i want to lead the climb then I just build a ground anchor and it will belay me as well.
It can do hauling work too!

gfdonc

17-Oct-2011
10:32:10 AM

I was in the same buying position last year.
I find my pro-traxion great for hauling. Nice being able to leave it clipped in. Make sure you get a large enough biner to fit the top hole and can rotate around it, the large DMM oval works a treat.
Mini-traxion haven't used but has a clear advantage of being able to be used for self belay.

Integrated locking/pulley device beats jumar+plain pulley for efficiency and simplicity.

Jayford4321

17-Oct-2011
7:52:56 PM

Defo would Not use a toothed device of any type for self belay.
yeah sure I did it when I was younger and had no understanding,
money, or clue what to buy, but now we all know it's not good.

ISC rope grab, check a Ferno site, cheaper and better than the identical rescuescender.

There are 26 messages in this topic.