Mechanical Advantage System - CMC Rescue MPD User Manual

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The MPD is designed to function both as a pulley and as a ratchet or
progress capture device in a M/A system. After lowering, there is no need
for a complex changeover between a lowering system and a raising system.
The one-way pulley inside the MPD applies friction during descent control
but serves as a fully functional, high-efficiency pulley while raising the
load. The MPD effectively locks the rope during pulley system resets with
minimal settling in distance. To convert to an M/A system, simply attach a
rope grab and traveling pulley to the Main Line and a simple 3:1 mechanical
advantage is created. The MPD has a built in Becket that can be used to
attach a change of direction pulley to allow higher mechanical advantage
systems to be built (e.g. simple 5:1 or compound 9:1), thereby eliminating
the need for a rigging plate. This keeps the pulley system neat and clean
with minimal loss of efficiency.
IN A MECHANICAL ADVANTAGE SYSTEM
Single
Pulley
Simple 3:1
M/A System
Single
Pulley
Double
Pulley
Simple 5:1
M/A System