Z-Pulley

  A Z-Pulley is a simple machine that is a vital for anyone traveling on a glacier. They make crevasse rescue much easier, especially in variable conditions. Knowing how to build a Z-pulley is important because often time, it is almost impossible to pull a victim out of a crevasse based on man power alone.


Method
    A basic Z-Pulley consists of 2 pulleys, 1-2 anchors, and some sort of directional rope stopper (such as a prusik or petzl stopper). The first step for building a z-pulley would be to build an initial anchor to take the force of the rope, leaving the climbers free to assemble the rest of the z-pulley. With two pulleys only one anchor is required. Below is an image of the basic assembly.

    
Image Courtesy of advdesigns.com


Once the Z-pulley is assembled, the mechanical advantage can be utilized to easily rescue crevasse victims.