The 3:1 Z-Rig is one of the quintessential mechanical advantage system used by rescuers. This system when offset requires 1/3 of the rope than the 4:1 block and tackle system.It can be converted easily to a 6:1 compound by the addition of a single pulley and is a powerhouse due to its ability to be modified while loaded if progress capture is in place.
With a few modifications the Z-Rig can give a Rescue Team as much as a 22:1 Mechanical Advantage. The Z-Rig is reasonably easy to rig, is easy to add a progress capture device and provides an appropriate amount of mechanical advantage to raise one or two people.
This system is paramount to a rescuer’s arsenal and will unlock true stroke advantage with minimal rope consumption while offering a multitude of benefits both vertically and horizontally.
Construction of the Z-Rig
1:1 Change Direction (CD)
When constructing a Z-Rig always start in the #2 Hole of the rigging plate. This will allow for additional mechanical advantage through the process of adding a 2:1 later if needed.
Start off by placing a carabiner attached to a prusik minding pulley in the #2 hole of a rigging plate.
Run a rope from the load or direction of the load through the pulley and back toward the load.
This creates a 1:1 CD
1:1 CD with “Progress Capture”
Add a “Progress Capture Device” such as a Tripple Wrapped Prusik in order to hold the load while resetting the system.
1:1 CD with Progress Capture and added pulley & carabiner
Add an additional pulley and carabiner in order to grab the load line. Run the rope through the pulley back toward the anchor. This will make a “Z” shape out of the rope. This is how the “Z-Rig” gets its name.
3:1 “Z-Rig”
Add a Triple Wrapped Prussik to the load line and connect it to the carabiner attached to the lower pulley.
Ensure all carabiners are locked.
Tension Analysis (click to enlarge)
Components (click to enlarge)
The IPS Group
Shayne Torrans – HSEQT Manager
1.281.479.4277 || www.theIPSgroup.us
