Excerpts from Rigging Lab Academy's ~ Confined Space Rescue: Technician Tripod (English) Reeve Overview
We can get into situations where either because the products that are coming out of the space are some sort of Ethyl Methyl death (where you don’t want a lot of people around the outside of the hole) or the hole is elevated or in another hazardous type of geography (where you only want a limited number of rescuers on the top of the space) where we want to rig what’s generally termed as a tripod reeve.
To start, we’ll build a simple English Reeve system and see it in play at the top of the space so that we can take a closer look at it.
First of all, we need anchors that are in line. If we have forward or back motion underneath our tripod, we can tip the tripod over. It’s essential that we have anchors in line, whether we’re rigging to a tension line in order to create a movable anchor over on the sides or just a solid point.
Secondly, we need swiveled pulleys or pulleys that have a swivel on them and we’ll use the Pro Traxion pulleys without the Pro Traxion catch being engaged. Place one pulley on each side. We need to add a middle pulley to the system. This middle pulley here does not have to be a swivel pulley.
What this now creates is your traditional English Reeve system. Because you have an equal pull on each pulley, when tension is pulled on the rope you start to “cheat” and “cancel” the resultants and generally the resultant comes back in line with the load. If you want to get into the physics, take a look at some of the other Rigging Lab Academy courses, particularly the Advanced Rigging Physics courses by Richard Delaney that dive into resultants and moving resultants.
Note that the anchors need to be in line with each other otherwise you risk moving the tripod which is not something you want to do. As you now pull, you’re pulling on a 2:1 so you can rig something like a 3:1 on the far side and you’ll a 6:1 mechanical advantage in total.
When you’re lifting the package out of the space, you only need one attendant up top to run a safety if you don’t want to run it remotely. That person should be checking on the package as they’re coming out of the space. Should that be a hazardous atmosphere, you only have one person on breathing air in the zone. If that area is a hazardous geographical location, you only have one person that’s clipped in.
Tripod Reeve - Top Side
The anchors, if you were looking above them, are off by about a foot which is not really a big deal because of the length of rope that we have in service. We’ve anchored very, very short on one side — very close to the leg of the tripod — and we’ve anchored very far on the other side. For reference purposes, we’re about six feet anchored on one side and about 35 feet anchored on the other.
The perfect location to run a tripod reeve is up in a crowded, tight location. You’ll notice in the next video that we’ve got our team member, Tony, up top in a danger zone as there’s fall hazards on three sides plus the hole in the middle. He can sit here and communicate back and forth with the ground team and the team leader to ensure that the package is moving and is not held up. Should this be a hazardous environment (such as bad atmosphere), Tony would be the only one on SCBA outside of the rescuers and the patient in the space.
As we haul on this system, the patient is connected to a 2:1 mechanical advantage which is being hauled on by a 3:1 mechanical advantage, giving us a 6:1 mechanical advantage system.
Tripod Reeve - Haul Side
Here we’ve got the bottom side of our tripod reeve on the ground level. Doing this allows our haul team to be on the ground here as well. The haul team has rigged up a 3:1 mechanical advantage system using a Petzl Rescucender, a Petzl RollClip, and a Petzl I’D or Petzl Maestro can be used.
We have one or two haulers down on the ground level to haul the load up and through the tripod.
Peace on your Days