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khu

Petzl Micro Traxion for glacier travel?

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I was wondering what some people thought of using the Petzl Traxion pulley at the harness for holding a fall on glacier travel. If you're not familiar with the device, it's a progressive capture pulley.

 

Here's the setup (except I'd have another biner holding the overhand knot at the chest coil, not on the same biner)

 

trax.JPG

 

I really like the idea of having the pulley already in the system (and progressive capture) after arresting the fall. Especially in a two person (on the rope) rescue situation because this enables me to just clip the screwgate into an anchor point and get myself out of the system without having to work the pulley around a prusik point. Having less at the anchor seems nice.

 

It also is very convenient for falling into the crevasse. This way, to complete my ascension system, I just connect my Petzl Basic and go, as the Traxion is amazing for ascending the rope and will already be in the proper set up.

 

The Traxion is rated to 4KN breaking strength for the progress capture, but the pulley as a whole is rated to 15KN. It seems if the progress capture failed, the pulley would just be loaded normally with the rope going to my chest coil.

 

 

I'm just toying around with a more modern setup, utilizing all the amazing gear that has been coming out recently. Let me know thoughts, problems, and other ideas!

 

 

 

 

 

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get myself out of the system without having to work the pulley around a prusik point.

putting the pulley with rope onto the biner holding the prussik is not that hard. at least when using a standard prussik. may be harder when using a mechanical device for a prussik.

 

 

It also is very convenient for falling into the crevasse. This way, to complete my ascension system, I just connect my Petzl Basic and go, as the Traxion is amazing for ascending the rope and will already be in the proper set up.

standard waist and foot prussik (texas kick system) are already on the rope and ready to go also without the need for more gear. while being nice, the Basic and traxion weight more than cord. Less is more,especially for something as infrequent as a crevasse fall.

 

 

 

The Traxion is rated to 4KN breaking strength for the progress capture, but the pulley as a whole is rated to 15KN. It seems if the progress capture failed, the pulley would just be loaded normally with the rope going to my chest coil.

 

why is the unit rated to 4kn while the pulley rated to 15kn? Is that the force that the teeth part breaks away from the unit?

what force does the teeth of the traxion cut into the rope? (that in itself could be the major downfall of your system)

 

If petzl doesn't explicitly describe the use for this, there must be a good reason.

Edited by genepires

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for a 2 person rope team, I have been using a system that I haven't heard of. Instead of a standard prussik between my harness and the rope, I used a short cordellete to make a single strand munter mule on a locker with a loop on the end to use for the prussik wraps. I wrapped it up with a little bit of cloth tape to keep it from accidentally coming undone while tromping around.

If my partner falls in deep into the crevasse, I simply unclip the locker from my belay loop and clip it onto the snow anchor to get the weight off me.

when I put in another snow anchor with the equalization between the two, I can release the munter mule and lower the rope till the weight is on the equalized anchor.

Is it overkill? probably. But then caring metal ascending gear is probably too.

 

hopefully you never get a chance to see if your setup is any better or worse than standard prussiks in real life. :)

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Petzl describes sheath damage occurring at 4.5KN, so I assume that's why the rate the progress capture limit as such.

 

In terms of weight, a 5-6ft prusik harness loop + a 11-12ft foot loop weighs about 258 grams (or less depending on diameter). The Traxion and Basic clock in at 170, so these items are indeed less weight than the cord. Also, with the prusik set up you'll have to throw in a separate pulley to the equation

 

I like the idea of carrying the Basic for using on fixed lines also, otherwise you'd carry the loops and an ascender, if you use the fixed lines.

 

Petzl does outline a setup for self belaying with the Traxion and many uses in crevasse rescue, but not specifically for replacing a prusik. I would imagine they don't address every possible application of their gear.

 

 

I understand it's not difficult to utilize the tried and true prusik setup, but I'm just curious about using new gear or if anyone else has experimented with these types of systems.

 

 

 

 

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One thing about prusik cords is that you can use them to build rappel anchors, something I have done countless times when I burn through all the tat I've brought. Can't do that with the Traxion.

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fuck no, dynamic falls of any kind on a toothed cam are seriously bad news, you wouldn't be caught by the coil around your body because the rope would be severed. If you want a lightweight adjustable device the grigri2 is perfectly suited for that purpose, and will not sever the rope if you fall on it.

 

Having said that, the minitrax is a incredibly awesome device, I have two for big wall applications, and bring them along for simul climbing.

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Personally, I would not use a Petzl Micro Traxion or any other toothed device (handle ascender, Tibloc etc) in any situation with the potential to shock load the device. I am sure you will get differing opinions on this topic. According to the Petzl user manual you can use a Micro Traxion in a situation that would have a fall factor of 1 or less. http://www.petzl.com/files/all/product-experience/SPORT/PE-MICROTRAXION-SP-EN.pdf Theoretically you shouldn't ever have a fall factor greater than 1 in a crevasse incident, however, I would much rather arrest the fall and then put the device into the system. To me it is just a risk versus a reward....potential risk is there and reward isn't very high (in my opinion).

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How would simul-climbing with the minitrax be different than glacier travel? When looking at a fall. I completely agre with you and the probability of rope damage, I just think its odd Petzl outlines these setups in their manual.

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In terms of weight, a 5-6ft prusik harness loop + a 11-12ft foot loop weighs about 258 grams (or less depending on diameter). The Traxion and Basic clock in at 170, so these items are indeed less weight than the cord. Also, with the prusik set up you'll have to throw in a separate pulley to the equation

 

Petzl does outline a setup for self belaying with the Traxion and many uses in crevasse rescue, but not specifically for replacing a prusik. I would imagine they don't address every possible application of their gear.

 

 

not sure what you are using for cord, but the 6mm cord runs at 22g/m and with your lengths it runs into 176grams.

 

they outline most every possible use of their gear but there is a chance that some possible uses are neglected. But they do explicitly write about not using it in a way to shock load the rope. Setting up a z pulley system with a device should not shock load anything. falling on it will which is why you don't see that option discussed.

 

I am curious though how you can ascend a rope with only the micro traxion and a basic ascender. shouldn't you need some kind of cord to attach the basic to a foot?

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How would simul-climbing with the minitrax be different than glacier travel? When looking at a fall. I completely agre with you and the probability of rope damage, I just think its odd Petzl outlines these setups in their manual.

 

I don't want to speak for how keenwash uses microtraxions during simu-blocks, but there was a technique for using tiblocs in simuclimbing. The tibloc is placed on the gear so that when the second person falls, the force is not pulling on the lead climber but right onto the gear. If the first person falls, it becomes a standard simu fall. Maybe he is using the micro in the same way, not on his harness.

 

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We used 1 micro traxion each as part of our 2 man glacier travel setup this year but we definitely did not have them configured to hold the fall. Seems ill advised as others have said. Note that the device can be pre-attached to the rope without having to hold the fall.

 

In the ascending scenario we use the traxion connected to the harness and a prusik for the feet. The primary benefit is that you don't have to fuss with unbinding and pushing up the harness prusik while you hold yourself up standing in the foot prusik, which can be a pain in the ass with cold hands/gloves and a thin diameter rope that causes the prusik to kink up on the rope.

 

Similarly we had problems getting our old prusik minding pulleys to mind the prusik properly when using an 8mm rope. The micro traxion resolved these issues and allowed us to carry the light rope. It is also lighter than the additional prusik and prusik minding pulley we used to carry.

 

I like that genepires came up with a way of actually equalizing the two anchors instead of the second one essentially just being a backup that is unlikely to be loaded equally unless the first one gives a lot.

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For the weight, I had pulled weights for 7 and 8 mm, which are what I had for an old 10mm rope. But I've recently picked up a smaller rope and will need to adjust my prusiks and yes, making them lighter.

 

I just didn't want to deal with prusik minding pulleys, as they've been a pain in the past. It seems safer to just stay with the prusik at the live strand of rope off my harness.

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noticed something to consider for single person rescue situation. if the weight is being held by the micro trax, you would not be able to take it off your harness and clip it to the snow anchor.

you would have to clip the picket sling to your locker, ease off and hope that you clipped it in a location that you can get yourself out of that locker. If your micro trax locker was clipped directly into the belay loop, this would be even more difficult.

 

that micro trax seems like a very efficient and light piece of gear though. perfect for glacier travel rescue.

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How would simul-climbing with the minitrax be different than glacier travel? When looking at a fall. I completely agre with you and the probability of rope damage, I just think its odd Petzl outlines these setups in their manual.

 

To simul with a microtrax you throw it on a bomber piece a ways above a crux section, that way if the second comes off they don't kill the leader. The microtrax feeds much better and doesn't automatically shred the rope, unlike a tiblock.

 

A TR fall is not going to have a very high fall force on it, also, if you're simuling you really shouldn't be falling.

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fuck no, dynamic falls of any kind on a toothed cam are seriously bad news, you wouldn't be caught by the coil around your body because the rope would be severed.

 

this. rope will be cut by 5 kn.

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I am not a fan of teethed insturments on my ropes. When I am top rope soloing I'll take a microsender over a traxion device just to avoid the teeth. The progressive capture is great for big wall applications, but it seems to me that a pulley and prussik cord will be more versatile in snow situations, and less likely to get jammed up with snow, more moving parts on traxion equipment.

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I don't want to speak for how keenwash uses microtraxions during simu-blocks, but there was a technique for using tiblocs in simuclimbing. The tibloc is placed on the gear so that when the second person falls, the force is not pulling on the lead climber but right onto the gear. If the first person falls, it becomes a standard simu fall. Maybe he is using the micro in the same way, not on his harness.

The same year tibloc came out, I heard of a guiding fatality in the alps attempting exactly what you describe here, and remember a notice coming out from Petzl to specifically NOT use a tibloc in this manner. Like it's been mentioned before, no ascender is intended to catch dynamic loads of any sort, and toothed ascenders will threaten to tear the sheath and possibly cause the rope to fail.

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This would be unfortunate

 

[video:youtube]

Edited by khu

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but it seems to me that a pulley and prussik cord will be more versatile in snow situations, and less likely to get jammed up with snow, more moving parts on traxion equipment.

 

Part of the benefit of teethed hardware is their ability to work on icy/snowy/muddy/wet ropes. I'd actually be interested in seeing test data for a prusik installed on a saturated rope vs dry rope. Not implying it's a good idea to employ the tiblock/microtrax in a dynamic situation, but just out of curiosity, it'd be interesting to know.

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I don't want to speak for how keenwash uses microtraxions during simu-blocks, but there was a technique for using tiblocs in simuclimbing. The tibloc is placed on the gear so that when the second person falls, the force is not pulling on the lead climber but right onto the gear. If the first person falls, it becomes a standard simu fall. Maybe he is using the micro in the same way, not on his harness.

The same year tibloc came out, I heard of a guiding fatality in the alps attempting exactly what you describe here, and remember a notice coming out from Petzl to specifically NOT use a tibloc in this manner. Like it's been mentioned before, no ascender is intended to catch dynamic loads of any sort, and toothed ascenders will threaten to tear the sheath and possibly cause the rope to fail.

 

thanks for sharing Chris. that is the kind of news that needs to get spread around to everyone. luckily I never had enough of those things to get into trouble.

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nope. would never rig the micro-traxion to hold a fall for reasons already stated. even in the relatively low load situation of a crevasse fall.

 

I do carry one on my glacier rack. they can make life significantly simpler in some situations.

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I don't use toothed devices to catch falls in crevassed terrain, even though the fall factor should never be anywhere even close to 1.

 

-Typical maximum free fall (not rope stretch) in crevasse situation ... 2 meters

-Typical minimum rope in service (team size dependent) ... 15 meters

-Typical maximum fall factor = 0.1333

-In reality, the peak force is absorbed significantly by a) a non-fixed anchor ... the person catching the fall and b) the rope cutting through the edge of the bridge.

 

Truly hitting a high fall factor in crevasse falls is nearly impossible.

 

You can easily adapt a regular pulley to become a prussik minding one two ways. Everyone knows the ATC trick, but a better one exists by simply cutting a plastic card. - I've written a blog post about it and lots of other pulley considerations for Oregon Mountain Community here:

OMC - Pulleys

 

 

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