What are these (woodworking?) clamps for?

I bought a bunch of clamps on craigslist. Most of them are C clamps or F clamps or bar clamps. Stuff that I understand. And then, there’s these ones. What are they for?

Those are jig clamps. They’re designed to hold the material to a work table.

The 2 with the thumb screws attach to a piece of flat bar, such as a flat bar clamp. And the other one is a bench dog clamp.

And similar versions fit onto a miter saw to hold down short pieces.

Ok, I see how the two with the thumb screws would work, but I’m still a little fuzzy on the other one. I’m used to bench dog clamps having a longer circular (or less commonly, square) bar that extends below the bench surface into the dog hole. But this one just has a flat bottom. How does it attach to the bench/dog hole?

It doesn’t. It slides into a groove.

Most likely those were specialized clamps that were part of a system designed to do a specific job. They’re not really general purpose clamps.

Yeah, I can see how I could slide the one clamp into a T-track or something, but it’s awkward that it doesn’t rotate. I could only clamp something in line with the track. I’ll probably just give it away.

The other two might be useful to provide clamping pressure to the middle of a large piece? If I can run a bar clamp across and slot into it. I’ll have to see if they’ll fit onto the bars of any of my F-clamps.

No. it rotates. there’s a piece missing. there should be a holddown bolt. basically a two headed cam that slides in the track and fits into the clamp. This one shows the bolt going all the way thru, but ive seen them as just a non adjustable bolt.

It’s all coming together now. Thanks!

Right, the T-nut portion is missing. These probably fit standard T-tracks. The T-nut diameter or long axis is likely 9/16". Here is a .pdf showing common dimensions.