Strength of 3 men, for only $20All of you should be familiar with the basic “Ellington” or “primitive” system. It uses 4 carabiners: 1 to hold the end of the line to one anchor; 1 hitched or line-locked about 80% of the distance from that anchor; 2 more at the other anchor, and a very ‘primitive’ looping of the remaining 20% of webbing distance to act as mechanical advantage. It’s the system I describe in this post. You can build a primitive setup for about $40-60 at REI.
Lately I’ve been trick-lining a lot, which means I want my lines super tight, and with summer over there aren’t as many people around to help me pull them tight. So I built a cheap “real” pulley system to act as a multiplier on top of the mechanical advantage of the 3:1 carabiner setup, so that I can put 800lbs of tension* into the line by myself (and I’m only 155lbs!). (*note: this was measured in April 2010 with a calibrated dynomometer and I was able to pull 450lbs using just the 3:1, and 788 using the 3:1 primitive with a pulley multiplier added on)
The left half of this pic (4 locking carabiners + 2 rappel rings) is my normal “primitive” system. The right half of the pic (60cm red sling, 2 pulleys, 7mm cordolette, 2 black diamond carabiners) is my “strength of 3 men” multiplier.
You can buy cheap petzl plastic pulleys for as little as $3.95 at REI (you need 2), or metal mini-pulleys from SMC or CAMP for as little as $13-15. At least 10-15 feet of accessory cord for around $9-14. And of course, two oval carabiners for $6/each. (Total: $29.00 – 55.00)
Alright. So now that we’ve bought our goodies. The setup to the left should look familiar. This is a 4 carabiner + 2 line locker “primitive” setup. If I have taught you to slackline, or helped you build a kit, this is what you should own. The last two images (below) are an oval + pulley + 12 feet of cord.
2: Run the cord to the anchor, through the second pulley (attached to the anchor somehow — either clipped onto the 2 carabiners there, clipped into the anchor sling, or clipped into a second sling like I have done).
3: Run the cord back to the first pulley, through it, and then pull.
The only downside with this setup is that every pull or two you have to “reset” the location of the carabiner that is attached to the tail. Also, you will likely find that the cord (if it’s 6mm or 7mm) is very “sharp” and hurts your hands to pull. This can be fixed by either wrapping it around a stick/rock/whatever, or a spare carabiner. In the last pic, you’ll see that I keep my keys on a 23Kn CAMP carabiner, so when pulling taut I just use this as a “handle”.