When belaying a raising, the tandem Prusik may be tended by the PMP as the belay line is pulled through it. For passing a knot safely, two sets of Prusik slings must be available. An LRH is required in case the Prusik knots lock up. After using the LRH, always re-tie so that it will be ready for its next application. The lowering system is shown in Figure 15.
Anchor plates connect the systems to the main anchors.
A Prusik starts to slip around 7 kN or 1540 lbs, which will avoid overloading the raising system. We use the LRH on the main anchor to secure the main line while reversing the system from lowering to raising and vice versa as described in the next paragraph. Rigging System for Raising Figure 15. Often, a quick change from raising to lowering or vice versa is necessary. It is important that the belay line is NOT used to hold the main line during this operation.