I only have one pulley. Where should I put it to get the easiest pull?
Excellent question! We often have to improvise with limited equipment, and the location of the pulley can make a huge difference in the efficiency of your hauling system.
You should use your “good” pulley on the position that’s closest to your pulling force (aka, your hands).
A simple explanation, in the words of rigging expert Richard Delaney: "...the best place is closest to where the effort is applied, as this preserves maximum effort moving into the system rather than wasting it at the first bend."
Or, to say it another way, any inefficiency at the first pulley is compounded throughout the system, so you want to your most efficient pulley closest to the pulling force (that’s you).
For a 3:1 (below), your pull is closest to the travelling pulley, so that’s where the good pulley should go.
A lot of folks think the pulley always should go on the moving part of the load to gain easiest pull, but this is not always true. Below, in the 2:1 with a redirect, the pulley should go on the anchor. Again, it’s because the anchor is closest to where you are actually pulling on the rope.
This may seem a little counterintuitive (it was to me!), but it's easy to set up a test and prove it to yourself. Get a pulley, a carabiner, a rope, something heavy, and an anchor point. Set up each way and notice the pulling force needed in each set up. In this case, a pulley on the anchor is better.
Confession: this did not intuitively make sense to me, so I did a little observational study to prove it to myself.
I set up a 2 to 1 system, redirected through a top anchor point, as in the diagram above. I had a 10 pound barbell weight, and attached an inexpensive spring scale to the pulling strand. I pulled at a slow steady rate, and noted the most common whole number reading on the digital scale while I was pulling.
2:1 - pulley on anchor, carabiner on load: 8.5 lbs. of force needed,
2:1 - pulley on load, yellow carabiner on anchor: 11.3 lbs. of force needed
2:1 - pulley on both anchor and load: 8.2 lbs. of force needed
Clearly, putting the pulley on the anchor is the best approach. I almost didn’t need a pulley on the load, as the force needed with a pulley or a carabiner on the load was almost the same.