The treadles on a loom are the pedals that control how the weaving structure forms as you weave. You attach one or more harnesses to each treadle so that when you step on the treadle, it's movement moves the harness creating a space or shed that you can throw your shuttle through. This is how the fabric is created. Generally, the more harnesses your loom has, the more treadles you will need.
Depending on the loom, the treadles may raise or lower the harnesses or do both at once. And depending on the loom, you may have four or 8 or 12 or more treadles. Once you get to 12, however, you generally graduate to a computer controlled loom in which case the computer controls all the connections and all you do is push down on a single treadle over and over. Yes, it's magic.
Right now, I'm weaving on my Gilmore loom. It has 8 harnesses and 12 treadles. That gives me enough treadles so I can attach my harnesses in all sorts of ways to make whatever pattern I want. I'm currently doing a pattern that falls into the "plaited twill" category. It doesn't really matter what the pattern looks like, although let me assure you, it's lovely. To make this pattern on my 8 shafts, I need to use 10 treadles. This is the first time I've ever done a pattern that called for 10 treadles.
I have said in the past that I'm treadle pattern challenged. If the treadles are used in any pattern that isn't easy enough for a 4 year old to grasp and remember, then I won't be able to follow it either. In this case, my pattern is 1-2-3-4-5-6-7-8-9-10-9-8-7-6-5-4-3-2... etc. I love how this patterns looks (it looks like leaves) and I'm thrilled to be able to produce it without getting lost in the treadle pattern.
I currently do have an issue, though. I have been battling a bruised tendon in my right ankle for the last 5 months. No, for those of you who might ask, this is not the ankle my dogs broke by knocking me down a couple of years ago. This is my "good" ankle. Ha!
Fortunately, I can push on the treadles with my right foot without any problems. What I find difficult to do, is push on the treadles with my right foot stretched far to the right. A couple of times now I have pushed my right ankle beyond its limit and ended up with a huge painful cramp that took a long time to subside.
My work-a-round for this is to sit farther to the right in front of the loom. Normally I would use my left foot for the 5 treadles on the left side of the loom and my right foot for the 5 treadles on the right. I'd split them in half. But that's not at all comfortable. So I use my left foot for the 6 treadles on the left and my right foot for the 4 treadles on the right. It feels a little weird but both my feet are very happy and now I can weave along for much longer than I could before. I'm happy.