ALWAYS PERFORM A SAFETY
CHECK BY UNLOCKING THE
PARKING BRAKE AND GIVING
A QUICK TUG ON THE LOAD
END OF THE ROPE TO ENSURE
PROPER RIGGING PRIOR TO
COMMITTING A LIVE LOAD
OVER AN EDGE.
WHEN RIGGED PROPERLY,
THE MPD WILL LOCK UP.
THE MPD MUST BE
PROPERLY RIGGED
PRIOR TO USE
.
BELAYING A RAISING SYSTEM
If the load is being raised, then the Belay Line can simply be pulled hand
over hand through the MPD. However, if the distance the load has to be
raised is greater than approximately 30 m (100 ft), it is recommended to
convert the Belay Line system into a simple 3:1 mechanical advantage
pulley system to assist with the raising of the load. The load can be raised
more effi ciently if the Belay Line assists with the raising, since it is possible
that a lower mechanical advantage will be required by the Main Line. This
will also take the stretch out of the line. For the fi nal edge transition, convert
back to a 1:1 system using only hand tight tension on the Belay Line by
pulling it hand over hand through the MPD.
MIRRORED SYSTEMS
Rope rescue systems, where both rope systems are capable of
simultaneously performing as a Main Line and a Belay Line are referred
to as Mirrored Systems. Unlike the MPD, most descent control devices
are incapable of performing both functions concurrently. Ideally, a true
independent Mirrored System is achieved with maximum fl exibility and
versatility when both the Main Line and Belay Line are each managed
with an MPD. This way either rope system can perform either function,
without the need for complex changeovers or function specifi c equipment.
Additionally, if an MPD is used for both the Main Line and Belay Line in a
Shared Tension System, then should either of these systems fail, the other
rope system can serve as a belay and the potential arresting distance is
minimized since both ropes will be prestretched.
!
Running End
Tug on
Load End
RIGGING THE MPD
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For the greatest system redundancy and therefore safety ensure the Belay
Line system is anchored and operated independently of the Main Line
system.
As with the Main Line, it is recommended that someone assist the Belay
Line operator by feeding rope to ensure there are no tangles or snags that
would cause the operator to unnecessarily stop the operation.
BELAYING THE EDGE TRANSITION
To ensure proper hand-tight tension of the Belay Line (such as during edge
transitions), fi rmly grip the load end of the rope with one hand and apply
friction, so that there is no slack in the rope between the load and your
hand. The other hand feeds the running end into the MPD so that the
rope is unseated from the sheave tread
. This will reduce rope drag on
the sheave and keep the MPD from inadvertently locking up. This technique
allows the operator to match the speed of the Main Line. In contrast, the
technique of trying to simultaneously shuffl e rope into and out of the MPD
will result in a repetitious start-stop motion of the belay rope and will likely
result in frequent unwanted lockups.
Applying Hand-Tight Tension
to the Belay Line
The operator is bracing his
arm on his leg to help maintain
a fi xed position of the friction
hand, while the other hand feeds
rope into the MPD.
THE MPD
NOTE
The Parking Brake is intended to
temporarily secure the MPD when it is necessary
for the operator to release their grip on the
running end of the rope.
If the MPD is to be left unattended, or if you
need to release your grip on the running
end of the rope for more than a short
time, lock the Parking Brake fi rst and
then secure the MPD by tying off the
running end of the rope around the
load end with an appropriate
tie-off method.
USING THE MPD
AS A BELAY DEVICE
FIRMLY GRIP RUNNING END OF ROPE TO ACTIVATE BELAY.
!
Feed In Running End
Load
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