darb Posted October 28, 2007 Share Posted October 28, 2007 (edited) Ok, so this will probably open a can of worms, but what are the thoughts on subbing a DMM Revolver biner for a biner and pulley for glacier travel? My only thought is that it would not be prussic minding. DMM Revolver Biner 44g DMM Shield Biner 32g Petzl Swing Side Pulley 55g Edited October 28, 2007 by darb Quote Link to comment Share on other sites More sharing options...
catbirdseat Posted October 29, 2007 Share Posted October 29, 2007 There isn't a whole lot of information out there but this has been discussed once or twice on this site, as well as rockcliming.com. One of the limitations of the Revolver is that 1) load limit is 11 kN, 2) the small sheave diameter means greater friction, compared to a blue pulley. However, I think that in a Z-Pulley 3:1 set-up, it would be ideal for use as the second pulley- the one that must be reset. This pulley sees less load than the other one, and it doesn't matter that it isn't prussik-minding. Quote Link to comment Share on other sites More sharing options...
wayne Posted October 29, 2007 Share Posted October 29, 2007 Im no mechanist but aint the size of the pulley wheel a factor? Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted October 29, 2007 Share Posted October 29, 2007 One of the limitations of the Revolver is that 1) load limit is 11 kN You would have to fuck up in a pretty big way to generate even half that much force in a crevasse rescue situation. Quote Link to comment Share on other sites More sharing options...
TrogdortheBurninator Posted October 29, 2007 Share Posted October 29, 2007 One of the limitations of the Revolver is that 1) load limit is 11 kN You would have to fuck up in a pretty big way to generate even half that much force in a crevasse rescue situation. And even then the actual biner is still rated to 24kN. Quote Link to comment Share on other sites More sharing options...
Bug Posted October 29, 2007 Share Posted October 29, 2007 I looked at these and wondered if they would be that great for a Z system. The small pulley size will decrease the efficiency by quite a bit but they would clearly be a lot better than a caribiner. Another useful application would be as a haul pulley. Quote Link to comment Share on other sites More sharing options...
catbirdseat Posted October 29, 2007 Share Posted October 29, 2007 I looked at these and wondered if they would be that great for a Z system. The small pulley size will decrease the efficiency by quite a bit but they would clearly be a lot better than a caribiner. Another useful application would be as a haul pulley. If my memory serves me, the efficiencies are as follows: Oval Carabiner 65% Revolver 75% Blue Pulley 85% Burly Rescue Pulley 90% Quote Link to comment Share on other sites More sharing options...
snoboy Posted October 29, 2007 Share Posted October 29, 2007 However, I think that in a Z-Pulley 3:1 set-up, it would be ideal for use as the second pulley- the one that must be reset. This pulley sees less load than the other one, and it doesn't matter that it isn't prussik-minding. Bzzzzzt! Both pulleys in a Z-drag see the same load, 2/3 of the total. It's gonna be better than a biner fer sure, but not as good as a burly rescue pulley - your choice when it comes down to weight. I know I have one in my ski box. The effect of pulley diameter on efficiency is also a function of rope diameter to some extent, AFAIK. So this might be fine in am ultralight spectra glacier rope kinda rig, but not so hot for the fuzzy 11mm out of the Mountaineers gear cache. Ooops! I think I just opened another can of worms! Quote Link to comment Share on other sites More sharing options...
swaterfall Posted October 29, 2007 Share Posted October 29, 2007 Use two of them at the first turnaround in your pulley system w/ a garda hitch for a lightweight self-tending system. Quote Link to comment Share on other sites More sharing options...
dylan_taylor Posted October 29, 2007 Share Posted October 29, 2007 Take the revolvers over the pulleys. They make quite a difference over regular biners as a training session will tell you. If you are a little person with a big partner, you might need actual rescue pulleys, and/or steroids. After teaching dozens of crevasse rescue seminars, I have seen that smaller, lighter folks, often represented by women, often have an incredibly hard time hauling their (heavier) partners out on even a 6:1. Outside help (other people) is often needed to break the static friction and get the victim moving. Moral of the story is hit the rowing machine heavy if your partner is bigger than you, and learn the 6:1 drop loop, and/or 5:1 direct haul. Also, garda hitch works as a great ratchet - disadvantage being higher friction, but advantage being longer haul distance (so once you break loose the static friction you can haul about 30 ft of rope (with only dynamic friction) without stopping. Drop loop systems have way less friction than direct haul systems during practice (and perhaps real life) rescuers often do a poor job of removing snow to create a clean lip (tighter, sharper angle is better than round lip) and a poor job of cleaning snow from beneath the load strand and from beneath the ratchet. Quote Link to comment Share on other sites More sharing options...
JohnGo Posted November 4, 2007 Share Posted November 4, 2007 "Petzl pulley, 55 grams" Y'all are quibbling about < 2 ounces here. There are many ways to shave that kind of weight without slightly compromising rescue gear. Consider saving the $$ and don't buy a Revolver. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.