RESCUE SYSTEMS 1
CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
CHAPTER 17 - ROPE RESCUE LOWERING AND RAISING SYSTEMS
PULLEY SYSTEMS
Many rescue situations require raising a victim from an accident site. To do this requires knowledge of
pulley systems so the rescue can be accomplished more safely and easily. By using pulley systems, the
rescue team can spread the weight of the load over distance. A 1:1 mechanical advantage means that a
100-pound load that needs to move 10' will take 100 pounds of force and 10' of rope to move 10'. A
2:1 mechanical advantage means it will take 50 pounds of force to move the object, but it will take 20'
of rope to move the object 10'.
Types of Pulley Systems
There are three classes of pulley systems. The Rescue Systems 1 course will work only with simple
pulley systems.
1. Simple: A simple system has all its pulleys attached to either the anchor or the load. One end of the
rope is tied to the anchor or the load and the rope is reeved through the pulleys.
L
Figure 17.1
Simple Pulley System
1:1 Odd
2. Compound: A compound system is one simple system pulling on another simple system.
L
Figure 17.2
Compound Pulley System
4:1
2:1 Pulling on a 2:1
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CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
RESCUE SYSTEMS 1
Complex: A complex system is any system that is a combination of simple and compound systems.
Figure 17.3
Complex Pulley System
5:1
RULES FOR DETERMINING MECHANICAL ADVANTAGE
There are three basic rules for determining the theoretical mechanical advantage of a simple pulley
system.
1. If the rope is tied off to the load, and the first pulley the rope goes through is attached to the
anchor, the advantage will be odd (1:1, 3:1, 5:1, etc.).
2. If the rope is tied off to the anchor, and the first pulley is attached to the load, the mechanical
advantage will be even (2:1, 4:1, 6:1, etc.).
3. If the last pulley in a system is attached to the anchor, it adds no mechanical advantage. It acts only
as a change-of-direction pulley.
To determine mechanical advantage, keep rules one through three in mind. Simply count the number
of lines between the anchor and the load. Do not count the line if it comes off a change-of-direction
pulley.
Components
Components needed to build a pulley system are:
1. Rescue rope

Most pulley systems can be built with 75' or 150' lengths of rope
2. Rescue pulleys
3. Prusiks

Hauling prusiks, to grab the rope and pull it into motion

Ratchet prusiks, to stop the rope from moving and allow the system to be reset
3. Anchor system
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RESCUE SYSTEMS 1
CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
SIMPLE 2:1 PULLEY SYSTEM WITH A CHANGE OF DIRECTION: LADDER RIG
This system is used to create lifting capability from anchor points located above the rescue team. It is
designed to pull down, toward the load. It is used in conjunction with ladder "A" frames, ladder gins,
and other systems where the anchor is above the load. The rope is attached to the anchor, run through a
pulley that is attached to the load, and back up to a change of direction pulley attached to the anchor.
This rig takes a rescue rope, two carabiners, and two pulleys. It should be operated with a belay line
and generally is used for short distance hauling.
2:1 Mechanical
Advantage
Figure 17.4
Ladder Rig
The actual mechanical advantage is less than 2:1 because of friction in the pulleys, rope abrasion, etc.
The mechanical advantage referred to in any system is the theoretical mechanical advantage, and you
should always assume that the actual mechanical advantage attained is going to be less in field
situations.
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CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
RESCUE SYSTEMS 1
SIMPLE 3:1 PULLEY SYSTEM: PIG RIG
This system is built in the same manner as the ladder rig but is used differently. It is designed to be
used horizontally rather than vertically. By attaching the rope to the load, then running it through a
pulley that is attached to the anchor, then back to a pulley attached to the load, the mechanical
advantage becomes 3:1. The pull will be away from the load. This system lends itself to being attached
to another rescue line with a hauling prusik. By hauling on the pig rig, the load attached to the other
line is raised with a 3:1 mechanical advantage.
Pig Rig
Load
3:1 Mechanical
Advantage
Main Line
Figure 17.5
Pig Rig
Pig rig is short for piggyback rig. Any system, such as a pulley system, which is attached onto another
system, such as a lowering system, creates a piggyback system. The two together are the piggyback
system, while the pulley system used to create it is simply called the pig rig.
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December 2000
RESCUE SYSTEMS 1
CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
SIMPLE 3:1 Z-RIG PULLEY SYSTEM
A 3:1 Z-Rig takes a rescue rope, two pulleys, and two prusiks to build. The rope is attached to a load
and run through a pulley that is attached to an anchor. The rope is then run back toward the load and
runs through a pulley that is attached to the rope with a hauling prusik as close to the load as possible.
(In most cliff rescue situations, this will be the edge of the cliff where the rope goes over.) The hauling
force is away from the load. This system requires a ratchet prusik located on the load side of the pulley
that is attached to the anchor. This ratchet grabs the rope and will not let the load drop back down if the
haulers should slip, or if any other component should fail. It also allows the forward hauling prusik and
pulley to be reset further down the rope (toward the load) as the load is raised.
Load
3:1 Mechanical
Advantage
Main Line
Figure 17.6
Z-Rig
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CHAPTER 17
ROPE RESCUE LOWERING AND RAISING SYSTEMS
Anchor
RESCUE SYSTEMS 1
Anchor
Attach ratchet prusik
and directional change
pulley to main line.
Load
Load
(1)
(1)
Anchor
Anchor
Four Bars Used For
Friction w/Single
Person Load
Release main
line from rack
& transfer load
to ratchet prusik
Single Person Load
Load
(2)
Anchor
(2)
Anchor
Lock Off Rack
When Lowering
Is Complete
Attach haul prusik &
mechanical advantage
pulley to main line
Load
Figure 17.7
RPM Lower
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Load
(3)
Figure 17.8
Change Over (No Change of Direction)
(3)
December 2000