Thread: Main line raising and lowering
12-16-2010, 11:14 AM #1
Main line raising and lowering
Was looking to see what others do for a raise lower system. Do you have each as there own independent system or do you have them tied together?
Example, the system that I use (for the most part) is to have the main haul line locked off to a descender. Connected to the descender is my MA. This gives the ability to raise the load stop and lower a full distance. It is clean and inline (allowing for everything to be in one field of view). The only area that is independent is the belay system, but that is kept simple as well with it just being the line, change of direction(double pulley in the case of having to use it as a haul, and a brake.
I have run into teams that find ways of making this very simple and I have seen some that seem to be in love with making it as difficult as possable.
How are all of you doing the job?
12-16-2010, 11:32 AM #2
I prefer my system to be anchor stap > rigging plate > descender (usually a rack) on one hole of the rigging plate, pulley w/ TTW prusiks attached w/ LRH (RRH) on another hole of the plate. This set up is commonly known out west as an RPM set up (with RRH in place of the mariner's hitch). I've found that this is one of the least complicated ways to rig the raise/lower without confusing guys who may not be as fluent in the rigging. We typically use a 3:1 with this system, however by swaping the anchor pulley and the traveling pulley it can easily be changed to a 4:1 if enough rope is available or a separate 4:1 can be bolted on if needed. The other set up I've been playing with is using an ID L in place of the anchor pulley. Mainly a 3:1 also, but by adding a few pulleys can be converted to a 4:1 or a separte 4:1 can be bolted on here also. No matter what configuration you use, I've found that if you do everything at the anchor instead of letting the descender travel while being locked off the system is more versatile. Not saying that the locked off descendr won't work, but it limits your throw and reset capabilities.John D. Calamia, BS, NREMTP, FP-C
12-16-2010, 11:43 AM #3
Lower: ID on mainline anchor plate.
Belay: TPB, no LRH, no pulley. Set of fours standing by with prusik in case you need to bolt on for releasing locked prusiks or passing knot.
Raise: Add travelling pulley for 3:1, progress to 5:1 complex if needed, and if need more, progress to 9:1 compound with a CD pulley attached to mainline plate. we commonly do this since we operate from roads/trails/bridges and a 90 deg turn down the trail works well for a haul field.
If the reduction in efficiency (66%) of the ID bothers you, dropping it out for a conventional PMP with a PCD prusik is fine too. Makes the changes between raise/lower a bit slower but still doable, especially with a SOF standing by.
-mMy opinions posted here are my own and not representative of my employer or my IAFF local.
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