The Prusik hitch has been around since 1931 when Dr. Karl Prusik created it while mountaineering in Austria. It is a hitch secured to a tight line and will slide when not weighted on a tight rope but jams solidly upon loading. It is recommended to use 2-3mm diameter less than that of the rope size and a prusik 35 cm length works best.
In rigging the tower, most crews are using the material handling Rock Exotica Omni-Block Swivel® with a side plate. This side plate is a prusik-minded pulley (PMP) to prevent drop loads either live or equipment. Prusik-minded pulleys are designed with an extended side plate to prevent a prusik hitch from entering the sheave when using a capture progress system. There have been many studies and tests done on the prusik and this friction hitch rigged with a PMP is a progress capture capable of holding 1,000 to 2,500 lbs. depending on the rope size and prusik cord size.
- Prusik must stay intact and snug when rope is hauling the load up.
- Monitor the rigging and assure the self-tending prusiks are well set up and working properly.
It is recommended to have someone monitor the prusik use. Tower Safety along with AHS Rescue have worked together to create a video on how to use a prusik minding pulley (PMP). Watch it here.
By Kathy Gill, Founder and CEO, Tower Safety & Instruction