I'm almost ashamed to admit that it's probably going to take more brain cells than I have to figure out what that thing is. I'm starting to suspect (as texastee2007 suggested) that it may be missing some parts. But even if this isn't the case, I'm still stumped. I've searched everything I could think of from A to Z, but still came up with zilch!
Again, unless it's missing something, I really don't think it's a type of jack. A jack would surely have some type of leverage feature, which the item doesn't appear to have. I printed a picture of it, and after studying it in great detail, certain features seem apparent to me, as well as some that still confuse me. For example ...
Note: All of the following is based entirely on "assumption" and "guesswork."
I'm convinced that ...
1. The pointed end of the rod is intended for driving into something like wood or the ground.
2. The gripping "foot" on the left is intended to support something.
3. The so called gear part with the handle - locking pin - chain - is intended to adjust the height of the "foot" and lock it in place.
4. The curved end of the rod is a handhold for positioning and pulling it out of whatever it was stuck or driven into.
What confuses me most is why the knobed handle is on the same side as the foot. It seems to me the handle would be in the way of whatever the foot supported.
So the bottom line for me is, it was intended as a "temporary tool" to hold something in position at various heights until whatever was being done was completed. With the following example as my best guesses.
After the rod was driven into the ground or wood - with possibly more than one being used at the same time ...
1. To hold a length of pipe in position until it could be fitted or soldered.
2. To hold a section of sheet metal or siding in place until it was secured. (But knobed handle on wrong side for this).
3. To hold a piece of wood or timber in place until it could be secured.
4. To hold wire in place (like on an electric or telephone pole) until the proper height or sag was determined.
I could list other examples, but you probably get my general idea by now.
In other words, I don't have a clue what it is, and suspect it will require someone who has seen one before to fully identify it.
If nothing else, maybe there is a clue to be found in my observations.
SBB