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BELAYING WITH THE MPD- LOWERING

Operating the MPD as a belay device, as with the main line function, involves an
assistant to help the operator in managing the rope. In order to create hand-tight tension
on the belay line, firmly grip the load end with a gloved hand and apply friction, so that
there is no slack between the load and your hand (Figure 94). The opposite hand
introduces rope into the opposite side of the MPD, which acts to unseat the rope from
the sheave. This action will reduce rope drag and prevent the MPD from inadvertently
locking up. This is a superior technique over shuffling rope into and out of the MPD,
which creates a start-stop motion with the rope and results in frequent lockups.

BELAYING WITH THE MPD- RAISING

During a raising evolution the rope can
be pulled hand over hand through the
MPD. If the distance of the raise and
rope in service is greater than
approximately 30m (100 ft), it is
recommended that the belay line be
converted to a 3:1 pulley system to
assist with raising of the load.
Efficiency is gained with the belay
sharing the load during a raise since a
lower mechanical advantage can be
employed on the main line. Additionally
this action takes the stretch out of the
line and reduces rope-induced rockfall.
The final edge transition is
accomplished without mechanical Figure 93- Belaying with MPD
advantage employed on the belay line,
which is managed with hand tight tension and rope is pulled hand over hand through the
MPD.

MPD EMPLOYED AS A PULLEY

The MPD can be used both as a pulley and as a ratchet or progress capture device
(Figure 95). The one-way pulley inside the MPD applies friction during descent and
serves as a high efficiency pulley while raising the load. After lowering, simply attach a
Prusik and a travelling to the line and a simple 3:1 pulley system is created. The MPD
also has a becket attachment hole that permits attachment of a change of direction
pulley for increased mechanical advantage.

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