| Technical Articles | Pulleys & Systems for Rescue & Industrial Rope Access
Victims in the field of rescue often times find themselves stranded
somewhere well above head level on cliffs, mountains, bridges, buildings and
other structures. The obvious challenge of importance to the rescue attempt is
the need to get the victim down. Any ultimate benefit from the rescue maneuver
hinges upon this one factor. Without success here there is no success and there
is no rescue.
How does one go about getting the victim down? Sheer brute strength can
serve the purpose however it is not always practical. Trekking an extended
distance while supporting another can result in the dreaded sewing machine knee
and/or the burning of the quads, neither of which is an enjoyable side-effect
the day after. Outside of helivacs,
pulley systems offer the ideal solution for
getting the victim down in the remote access areas often presented to rescue
When it comes to
pulleys the force of gravity
can be used to assist in the work while the use of friction on a rope is used
to control that force. Gravitational forces and the friction used
to control a descent are the integral principles of a rescue technique. This
harnessing of the power of both the force of gravity and the control factor of
friction can reduce the need for manpower and equipment while allowing for a
system in which things move quickly to evacuate the patient package in timely
However, down is not always the path of least resistance or the quickest
route to the rescue termination. Moving the victim up may sometimes be
necessary, prudent and expedient particularly when the vantage point of
additional rescue resources mandates an attack from above rather than below. In
a rescue strategy of upward evacuation the forces of gravity can work against
the team's effort; but even so, in many cases there are effective methods by
which the overall effort invested into the rescue can be greatly minimized.
So how does a team overcome the gravity working against the upward
direction of such a rescue? Just as
pulley systems are the ideal solution for
getting the victim down, so too they are the answer here. The various ropes and
pulleys incorporated into
pulley systems are the preferred, lightweight
option to counteract these forces of gravity when working in remote areas. To
help compensate for the many variables, obstacles and challenges thrown at a
team in the field a thorough assemblage of pulley system components along with
a thorough knowledge and understanding of the principles of
pulley systems and mechanical advantage will
go a long way in preparing the appropriate logistical solution of attack.
The history of the development of civilization is chock-full of examples
of men working with their hands using simple, compound and complex
pulley systems. A system of tools so simple
was at the core of powering the industrial revolution that set America on the
road to resources development and economic power. The simple tools that proved
so beneficial to our predecessors will likewise serve well those brave men and
women rushing to the heights to the aid of the unfortunate, stranded victim.
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The usefulness of
pulley systems extends well beyond simply the
lifting of the rescue package:
- LIFTING the rescue package is what first comes to mind
- LOWERING under control (river rescue)
- SMALL JIGGERS(adjunct tasks, scoops, pick offs, etc.)
- LINEAR ANCHORS (between anchor points called pretensioned backties)
- GUYING of artificial high directionals at the edge
- APPLYING-HOLDING TENSION
- POSITIONING within space
In addition to lowering load packages
pulleys are used to haul a load upward and to
move objects in any direction and many times their use incorporates a
multiplicity of directions of movement such as in the raising/lowering of a
person in a rescue situation. Some
pulleys have an integrated rope clamp to make
certain tasks easier. Certain
pulleys also allow for movement along a rope
or cable, again… for moving loads or evacuating a person. Tower Rescue,
Confined Space Rescue and Industrial Rigging are excellent examples of
Pulley systems for hauling, lowering and
holding require a very clean working knowledge of the equipment needed and the
challenge that is presented. Some examples can be seen in the following videos…
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An optimum advantage of comprehending
pulley systems is the fact it frees the
rigger to assemble the system specific to the need. The following are key
considerations before building a pulley system:
- Hauling area — What space is available for the hauling team?
- Throw length — What is the throw length? Is it sufficient?
- Haulers present (input) — How many haulers are available for the
task to be undertaken?
- Load to be lifted (output) — The actual mass to be lifted:
Climbing, rescue or extreme rescue load. Highline tensioning?
- Rope needs — How much rope is available for the pulley system
you intend to construct?
- Equipment needs — How much equipment is available for the task
you intend to undertake?
- Hauling area incline — Can you pull downhill? Wouldn’t you
- Adaptability — Can you easily change the mechanical advantage?
- Resetting — Resetting can use valuable time & energy. Does
the pulley system minimize this?
- Lowering ability — Can the pulley system lower easily under
control? Also, will it respond quickly? River rescue? Live bait?
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Simple, Compound, & Complex Pulley Systems
- SIMPLE: The rope is tied to either the load or the anchor and is run
alternately through pulleys on the load or the anchor until the
loose end finds itself in the grasp of the pullers.
- COMPOUND: A simple pulley system pulling on the end of a simple
pulley system. (Each simple system is referred to as a component of the sum.
May be more than two components)
- COMPLEX: A pulley system that is neither simple or compound.
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An established nomenclature serves to keep everyone on the same page in
terms of what words are used for communication in any given system of
specificity. Definitions of the words used within any nomenclature are key to
insuring everyone using it is speaking the same language. Some of the terms in
the nomenclature listed here may vary from terms you have used to describe the
- PULLEY: A small grooved wheel used with a rescue rope to change the
direction and point of application of a pulling force and in combination (as in
pulley system) to increase the applied force especially in a raising operation.
- PULLEY SYSTEM: An assemblage of rope and
pulleys used to increase the force to the
level required for the lifting or tightening to be undertaken.
- CHANGE OF DIRECTION: A pulley on the anchor closest to the haulers
(cd or cod). A cd adds no mechanical advantage to the system.
- DIRECTIONAL: A Pulley or
pulleys between the pulley system and the
load to be raised (d). Both low and high directionals are common. Not to be
confused with a change of direction.
- GANGED PULLEY SYSTEM: Any pulley system which is attached by a haul
grab to a second main rope for the purpose of lifting or lowering a load.
- IN LINE PULLEY SYSTEM: A system where the rope lifting or lowering
the load and pulley system are one and the same.
- THROW: The available distance between maximum pulley system extension
and two-block (Note: Simple pulley systems have only one throw. Compound pulley
systems have a minimum of two throws)
- HAUL FIELD: The available distance a hauler or haulers can run out or
the space that they have to stand and pull
- HAUL GRAB: The rope grab closest to the load in any pulley system
throw or compound pulley system component throw
- PIGGYBACKED: A compound pulley system with like same components.
Example: (2:1) (2:1) (2:1)= 8:1 piggyback (3:1) (3:1)= 9:1 piggyback
- TWO BLOCK: The point at which the throw of any pulley system or
pulley system component is collapsed. Also known as Chock-o-block
- RESET: The act of extending the pulley system throw out after
- RATCHET: The progress capture device allowing resetting of the pulley
system after two block
- RATCHETMAN: A person who tends the ratchet for up or down on the
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Acronyms (Used for pulley system notation and written
||Progress capture device
|Abt or PTBT
||Ratchet prusik (Type of
||Ratchet camming device
(Type of PCD)
||Change of direction
| Rock Exotica's Aztek Pulleys are
Perfect for the Job
Every aspect of the
Aztek pulleys has been optimized for the job.
They have built-in swivels. There is no conventional becket because that would
give an unwanted increase in length. Instead the rope end is held on the side
of the pulley so the pulleys can be pulled very tightly together when needed in
operaton or for storage. The two pulleys are different colors to match up with
their attendant Prusiks. The Prusiks are quickly activated with a quick release
pin. Of course, the sheaves are all ball bearing.
Complete system with two
Aztek pulleys, main rope (8 or 9mm), two
Prusiks and a travel restrict Prusik.
While using a complete system is highly recommended, the
pulleys are available separately for those
building their own system.
Strength as a system, even with 8mm rope, is 36kN.
Here is a compact mechanical advantage system that continually amazes
rescuers with its many uses and versatility.
Some of the uses are as a pick off, travel restrict, adjustable
directional, high directional guyline, high angle attendant tether, high angle
litter scoop, load release hitch and much more. Both Aztek pulleys have their
own color-coded Prusik and can be easily activated or deactivated. This means
you can have the ratchet at either the top pulley or the bottom pulley. The
special 3 on 2 Prusik cannot come off the rope, so the deactivated Prusik will
stay ready to be used as soon as you need it. Complete systems use sewn Prusiks
and a sewn eye on the main rope, which makes things neater and more compact
than knots. You cannot appreciate how smooth and easy use of the Prusiks is
until you experience it. Because the Prusik only sees a fraction of the total
load in an MA system, they don't get too tight and they are easy to release and
This system grew out of extensive use and experimentation of small MA
systems. It is light years ahead of anything else. If the world as we know it
ends and you need an MA system to help you rebuild civilization, this is the
Petzl Confined Space Diagram
Petzl Rescue Evacuation Diagram