The single pulley Cpulley
Smaller groups without enough muscle to pull the climber out by brute force need a more sophisticated system. The single pulley gives rescuers a 2-to-l mechanical advantage, doubling the amount of weight that each puller can raise (although friction somewhat lowers this ratio).
Several considerations enter into a decision to use the single-pulley (also known as the C-pulley). The fallen climbcr must be conscious in order to help by clipping into the rescue pulley. A separate length of rope is needed, either an unused end of the accident rope or another rope entirely. This method is, in fact, a good alternative to consider if the accident rope itself is embedded in the edge of the crevasse and won't move.
To carry out a single-pulley rescue (fig. 13-11), follow these steps:
1. Find a rescue rope. It must be at least twice as long as the distance from the anchor to the fallen climbcr.
2. Attach one end of the rescue rope to the existing anchor or to a new rescue anchor. (If the unused end of the accident rope is long enough to be used, tie a figure-8 loop in it a few feet beyond the rope's attachment to the anchor. Clip this loop into the anchor.)
3. Double the rescue rope into a big loop and attach a pulley with a locking carabiner.
4. Lower the loop with the pulley and carabiner down to the fallen climber. Tell the climber to clip the carabiner into the scat harness. Confirm that this has been done. Then tell the climber to take the strand of rescue rope that you will be pulling on and to run it through the carabiner at the chest harness, to help stay upright. Tell the climbcr precisely what to do.
5. Be sure the rescue rope runs over an ice axe or
other padding at the crevasse edge to keep it from digging in.
6. Haul on the unanchored end of the lowered loop. As you haul, the climber can grab the anchored half of the loop and pull up. This relieves weight on the rope and makes hauling much easier.
7. A rescuer must attend to the original accident rope at the anchor and pull slack through the friction knot or ascender as the climber is raised. This keeps the accident rope ready at any time to accept the climber's weight again, in case of emergency or if the pullers need a rest.
Continue reading here: The Zpulley
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