Smc crevasse rx pulleys - Mountain Buzz
 



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Old 01-04-2017   #1
 
Santa Cruz, California
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Smc crevasse rx pulleys

Hi all,

I'm shopping for some pulleys for my rescue kit and I was wondering if anyone has any input on the smc crevasse rx pulleys. Has anyone used these?

I'm wondering about them because they are quite a bit cheaper than a lot of the pulleys offered by other companies, or also other Smc pulleys but the specs seem the same. I'm not knowledgeable about climbing equipment and I can't really tell the difference between them but I'm wondering if I'm missing something.

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Old 01-04-2017   #2
 
Denver, Colorado
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I have some 20 year old SMC pulleys from my mountain days, and I'm planning to use them as part of a pin kit. The only issue I can think of with a small pulley, since the breaking strength seems good enough, is that a small diameter pulley puts a sharper bend in a rope, which adds a little resistance. But I'm no whitewater rescue expert; curious what others will say.
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Old 01-04-2017   #3
 
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That is the same pulley NRS sells. I have three of them and have used them. They work just fine. As for putting extra stress on a rope because of the small diam, I just use someone else's throw rope, haha
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Old 01-04-2017   #4
 
Santa Cruz, California
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What size ropes are max?
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Old 01-04-2017   #5
 
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probably 11mm.
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Old 01-05-2017   #6
 
Santa Cruz, California
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Quote:
Originally Posted by curtis catman View Post
That is the same pulley NRS sells. I have three of them and have used them. They work just fine. As for putting extra stress on a rope because of the small diam, I just use someone else's throw rope, haha
Good to know. If NRS is selling them they should be pretty decent at least. I just always get a little worried when I see a bunch of similar products, but there is one that is significantly cheaper than the rest. Makes me wonder if it is some cheaply made piece of junk and the last thing you need when using a z-drag is having something snap and send parts flying all over.
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Old 01-05-2017   #7
 
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If you go on REI and lookup pulleys, there are a bunch of other ones similarly priced from Petzl, Black Diamond and CAMP USA (a couple within a dollar and a few others within $10) so I wouldn't worry about it too much. They all have similar load ratings.

This is a bit of a thread hijack, but one thing to think about, and I don't have an answer for this, is that most climbing gear is rated in kN aka Kilo-Newtons. This is a force rating and my understanding is that most climbing hardware is designed for shock loading (i.e. falling and being caught be the gear) and not sustained force (trying to pull a stuck raft off a rock). In one situation you put a ton of force on it in an instant and then it just has to hold your weight and in the other it has to hold it for long periods of time.

I've tried doing a basic search, but I'd be curious to know how people with more experience interpret load ratings for stuff like pulleys and carabiners. Most of the pulleys in the size and price range that the OP is asking about can take around 20-24 kN of force and I'm sure there is some safety factor built in. 22 kN is bit less then 5000 pounds of force. I'd suspect the rope would break first, but when you are talking about mechanical advantage systems with load holding its not particularly hard to get up into that range.

Food for thought....kinda makes me want to get something designed specifically for the job. That said, anything is better then using straight carabiners as pulleys. It think the pulley axle would hold, but I'd be a little worried about the plastic pulley wheel aka sheave breaking under sustained load.
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Old 01-05-2017   #8
 
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Rivertown, West Virginia
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Electric, I work around cranes and the shives on modern ones are some type of nylon. Dont worry about it caving in. As you said the rope will break first. No mater how many pulleys you use the section of rope atached to the raft is seeing all the load. And shock loads will break something faster than steadily applied loads.
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Old 01-05-2017   #9
 
Wheat Ridge, Colorado
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The raft will tear before the rope or the pulley will break, assuming the rope and the pulley are in good shape.
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Old 01-15-2017   #10
 
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Smc crevasse rx pulleys

That particular pulley has a nylon bushing. Its purpose is to haul a 150-200 lbs of best friend out of a canyon, not several thousands of pounds of pinned raft off a rock. The axle probably won't break, I just worry that the bushing won't perform very well when subjected to that much force. I could see it deforming or binding under that much pressure and seizing up. Not the end of the world, just more friction. Or, maybe it'll work just fine. Who knows. I do know it's not rated for a Tyrolean traverse though. Probably because the friction will melt the bushing when you start the traverse. At least it's got a bushing and not bearings that will rust and seize up.

SMC's Swiftwater pulley's bearings don't seem to work after a couple of years. On my swift-water course several of them were really stiff. The instructor said they weren't that great. I read somewhere else that was because the "sealed" bearings were rated against dust and not water.

Because of that, I got the NRS / Omega Pacific rescue pulley with the bronze bushing. Bomber.


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