Excerpt Taken From Rigging Lab Academy's ~ Confined Space Rescue: Technician course Confined Space Rescue Split 4:1 Introduction
If you don’t have access to a Grillon or small mechanical advantage systems like an AZTEK or a set of fours, this is still an easy go-to.
- To begin, dead-end the rope in the system (to the tripod head). Then grab some pulleys (swivel pulleys work the best) and clip the first pulley into the system creating a 2:1.
- You then want to grab a pulley that has a capture on it. This pulley goes to the tripod head. By doing this, we’ve created a 2:1 with a capture device at the tripod head.
- Now, the first pulley is going to go to the feet of our patient. Then go down the line, take another pulley, and clip it in. This pulley will go to the head of the packaging device and then into another capture device at the tripod head.
In doing this, you’ve created a 4:1 mechanical advantage with single pulleys which will allow you to split the system as the need arises once you get the patient closer to the top of the space.
Why Would We Use This?
We use this setup if we don’t have a lot of overhead height. So as an example, if we’re on top of a vat or silo at a brewery, we can be only 2-3 feet to the ceiling. In situations like this, it’s crucial that we have something that enables us to get a full-size body out of the hole in stages.
Split 4:1 Operations - Bottom Side
We have brought the first pulley down to the foot end of the package and hooked it to the patient package.
We have the first pulley that’s going to be removed at the head. This pulley will come off first as we raise the patient up. During this operation, you’ll have the patient attached to a safety line. We have the patient “janed” (using a Petzl Jane) or tethered or lanyarded into that safety line directly. We have the patient in Class II harness and this allows the patient to have their own independent safety with their “mainline” being the rigging of the packaging device and their safety being their Class II harness directly into the safety line.
As they move the package up, the rescuer lifts the head and goes into a vertical orientation. This allows the patient package to move up through the hole vertically while keeping the pulley separated on the actual system
Split 4:1 Operations - Top Side
We’ve got our terminated end into the top of our AHD. This line is then going down to a pulley at the feet. This line is then coming up and through a pulley with a capture device on it.
We’re using a Petzl Pro Traxion but you can use a pulley with a prusik in here instead or whatever you have that will help satisfy that requirement. In our example, the Pro Traxion is locked. The line then goes back down, and a 2:1 is attached to the head. The line comes back up through another capture pulley (in our case, another Pro Traxion) that’s locked to our hauler.
So, we have our 4:1 mechanical advantage system split into two separate pieces (two 2:1 mechanical advantage systems) both at the top and at the bottom which allows us to take a 2:1 out of the system as required.
We used a Petzl ASAP in a pitch head configuration for our safety line and run it more as a pitch head style from the tripod. You could also run a tandem prusik belay or some other belay device up here.LETS MOVE SOME
As we mentioned earlier, the package will move into a vertical orientation. The whole idea of the split 4:1 is being able to split the 4:1 system when we get to a spot where we cannot get the patient physically out of the hole. With the Pro Traxion locked off, we have the ability to leave the package for a minute and to raise the package slowly by hand, which allows us to take the top of the 4:1 out.
We now have the feet on a 2:1 mechanical advantage system. The limiting factor now becomes hooking the toes on the edge of the space. You can haul with the 2:1 until you can get to a point where you’re out of this space. You can now bring it down, and the other rescuers can rest the patient on the edge of the space.
Gear Used In This Blog
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