best pulley for crevasse rescue

As title says, I'm looking for a pulley for crevasse rescue, not training, bag hauling, and so on. 

Tests show that a simple carabiner and rope can add lots of friction, so with a party of two, trying to give ourselves the best chance, I'm looking for a high quality, strong, low friction pulley.  No need to bring up the DMM revolver caraboner or similar, or the Petzl Ultralight plastic pulley--I don't think they would help here.  

The standby seems to be the Petzl Partner

https://www.petzl.com/INT/en/Sport/Pulleys/PARTNER

The DMM Polo Micro pulley looks promising, but is is strong enough?  And is the effeciency high enough?  The 6mm rope limitation is not a problem--For pure glacioer travel, I often use a 6mm rope with big blocker knots).

https://dmmwales.com/professional-products/pulleys/polo-micro-pulley

Any other ideas?

DMM Revolver locking carabiner.

https://dmmwales.com/climbing-products/locking-carabiners/revolver-1

Compared to the Partner, are you willing to take an extra 30g to have a Microtraxion?

B G wrote:

Compared to the Partner, are you willing to take an extra 30g to have a Microtraxion?

My standard kit is a DMM Revolver, Petzl Tiblock, and Edelrid Spoc.  

Kai Larson wrote:

DMM Revolver locking carabiner.

https://dmmwales.com/climbing-products/locking-carabiners/revolver-1

Did you read the full text, or are you trolling :)

My understanding is that the Revolver is designed to reduce rope drag--it's not a real pulley, and in tests performs the same as or worse than a round stock carabiner and rope.  

B G wrote:

Compared to the Partner, are you willing to take an extra 30g to have a Microtraxion?

Hey BG--definitely willing to carry to Microtraxion--I usually have one with me.  To make a simple dropped loop, and top add anymore MA, you need a progress capture system and at least one other pulley or substitute...hence the question.  

How about a Nanotrax and the DMM Polo micro pulleys...just dreaming.  Impractical, I think.

Bruno Schull wrote:

Did you read the full text, or are you trolling :)

My understanding is that the Revolver is designed to reduce rope drag--it's not a real pulley, and in tests performs the same as or worse than a round stock carabiner and rope.  

Your understanding of the Revolver's use is inconstant with my experience.  That is why I encouraged you to use one, in spite of your predisposition against it.  

The Revolver is a "real" pulley, and it significantly reduces friction effort in a hauling system when compared with a normal carabiner such as an Attache.  

If the "tests" you are referring to are the ones posted by "Alpine Savvy," you may want to try running those tests yourself, using a much heavier weight, somewhere like 80 or 100 pounds instead of 10 pounds.  10 pounds is not enough weight to cause deformation in the rope as it presses against the carabiner radius.  Raise the weight significantly, and I think you will find that the Revolver decreases the effort significantly.  

Also, the rope diameter may have an effect on the testing.  I use an 8.9 mm single rope for my glacier travel routes, which fits nicely into the Revolver pulley.  A fatter rope may not be as efficient.  

just pick any decent pulley and hope you don't have to use it.

Bruno Schull wrote:

Did you read the full text, or are you trolling :)

My understanding is that the Revolver is designed to reduce rope drag--it's not a real pulley, and in tests performs the same as or worse than a round stock carabiner and rope.  

Just get the Petzl Rollcip if you were looking at the DMM Revolver

SMC makes good ones you can find at rei for around $20

Kai Larson wrote:

Your understanding of the Revolver's use is inconstant with my experience.  That is why I encouraged you to use one, in spite of your predisposition against it.  

The Revolver is a "real" pulley, and it significantly reduces friction effort in a hauling system when compared with a normal carabiner such as an Attache.  

Hi Kai--thanks for the info. Glad the revolver is working for you. I'm happy to be proven wrong about the Revolver, but honestly I'm not sure.

My statement was based on the Alpine Savvy results, and also on some results posted by Jim Titt (who tends to be right about these sorts of things) here on this thread:

https://www.mountainproject.com/forum/topic/122287419/6mm-micro-pulley

He used an 88 kg mass, and a 4 mm line (more for a rock climbing rescue system).  He did not test the Revolver, and the cord surely make a difference of some kind, but his results for a carabiner and rope (60%) and a Petzl pulley (86%) are comparable to the Alpine Savvy results, so I'm not inclined to beleive that the Revolver would be significantly  more efficient with a higher mass or a different rope.  There are many variables, but I don't think the diameter of the wheel is big enough, to say nothing of the friction in the interface between the sleeve and the carabiner.

The Edelrid Axiom has a posted effeciency of 86% and a weight of 69 grams.  If the efficiency is really that high, that could be a nice option.

The Petzl RollCLIP has a posted effeciency of 85% and a weight of 110 grams.  That's getting a little heavy for a dedicated carabiner/pulley, but maybe it's worth it. 

Anyway, I'm still hoping there might be a very light, small, high effeciency, swing gate pulley out there somewhere.  Anybody play with the DMM Polo Micro?

I've been carrying and using an Edelrid Axiom as my random pulley for climbing, route development, etc. (ascending, reducing rope drag, emergency haul/rescue systems) and its wonderful to use. I've done mock rescue scenarios where I'm doing hauls and it gets more than my bodyweight on it. Definitely feels like it lives up to its posted efficiency. I've used a revolver before for the same and didn't like it. The axiom felt like a big upgrade. It lives on my harness 24/7 now.

"I'm looking for a high quality, strong, low friction pulley." 

Petzl Partner it is! 

The axiom looks and sounds cool but the Partner is only 56g + carabiner of your choice for a much bigger sheave and more versatility. Why not just copy or purchase the crevasse rescue kit? 

Is no one on the Petzl Rescue pulley?

Bruno Schull wrote:

Hey BG--definitely willing to carry to Microtraxion--I usually have one with me.  To make a simple dropped loop, and top add anymore MA, you need a progress capture system and at least one other pulley or substitute...hence the question.  

How about a Nanotrax and the DMM Polo micro pulleys...just dreaming.  Impractical, I think.

Why not carry a micro trax and an nano trax? The micro can act as your pulley, is high efficiency, swing gate, and give you the option of using it for other roles if necessary by engaging the cam. For a very marginal weight penalty you'd get more use cases out of the same gear. 

If you want something very specifically for crevasse rescue you could consider a CT Cric https://www.climbingtechnology.com/en/outdoor-en/pulleys-and-ascenders/pulleys-ascenders/cric

Is 150g but combines the pulley and rope grab into one thing, which saves on a krab.

Nun Ya wrote:

Is no one on the Petzl Rescue pulley?

That thing is massive for a recreational crevasse rescue kit. I *have* carried pulleys in the past, and do own a DMM revolver, but aside from a micro or nano, I don't carry pulleys anymore.

Bruno Schull wrote:

Hi Kai--thanks for the info. Glad the revolver is working for you. I'm happy to be proven wrong about the Revolver, but honestly I'm not sure.

My statement was based on the Alpine Savvy results, and also on some results posted by Jim Titt (who tends to be right about these sorts of things) here on this thread:

https://www.mountainproject.com/forum/topic/122287419/6mm-micro-pulley

He used an 88 kg mass, and a 4 mm line (more for a rock climbing rescue system).  He did not test the Revolver, and the cord surely make a difference of some kind, but his results for a carabiner and rope (60%) and a Petzl pulley (86%) are comparable to the Alpine Savvy results, so I'm not inclined to beleive that the Revolver would be significantly  more efficient with a higher mass or a different rope.  There are many variables, but I don't think the diameter of the wheel is big enough, to say nothing of the friction in the interface between the sleeve and the carabiner.

The Edelrid Axiom has a posted effeciency of 86% and a weight of 69 grams.  If the efficiency is really that high, that could be a nice option.

The Petzl RollCLIP has a posted effeciency of 85% and a weight of 110 grams.  That's getting a little heavy for a dedicated carabiner/pulley, but maybe it's worth it. 

Anyway, I'm still hoping there might be a very light, small, high effeciency, swing gate pulley out there somewhere.  Anybody play with the DMM Polo Micro?

 

All this discussion made me decide to do my own tests.

Hoisting a 35 pound kettle ball using an 8.9mm rope.  Rope running vertical up and down.  

Revolver carabiner:  57 pounds of force required

Round stock carabiner (CTConcept)   79 pounds of force required.  

This confirms my experience with the Revolver.

I could not get a measured test with a heavier weight, as my scales can only measure up to 100 pounds, but when I tried the same set-up with an 80 pound dumb bell, the pull with the Revolver was dramatically easier than the pull with the carabiner.  

Bruno Schull wrote:

Hey BG--definitely willing to carry to Microtraxion--I usually have one with me.  To make a simple dropped loop, and top add anymore MA, you need a progress capture system and at least one other pulley or substitute...hence the question.

Diverging a bit from the original topic, this AMGA video uses just one Microtrax (carabiners at fallen climber and z-drag) and he doesn't seem to have any issues lifting his partner: https://youtu.be/XXRf4fCyass

If you and your partner are each carrying 1 micro/nano, you can use both in the system (your partner's on the drop loop and yours on the progress capture).

Bb Cc wrote:

Interested, but: sounds like a one to one direct lift is only 35 lbs?

Direct lift is 35 pounds.

The Revolver adds 22 pounds of friction 

The carabiner adds 44 pounds of friction.

In a simple single pulley system, there is no mechanical advantage, so all you are getting in return for the friction is changing the direction of the force (down instead of up.)   All I was trying to do here is to get a measure of which one introduced less friction.  The Revolver was the clear winner.  

In order to gain any mechanical advantage, you would need to either attach the pulley to the kettle ball and pull upwards, or you'd need to introduce a second pulley into the system.  

While the static condition is relevant you should note that pulley efficiency is measured with a constant hauling rate, it is not clear exactly how you measured yours. We use a powered hauler through a strain guage and with the expected load (which is very important).