This is used to level a machine unwind. I am trying to develop a scaled down version of one. Not sure of what the assembly would be called or the bolt used in it.
I would call it a lead screw, they are typically pairs with some sort of linear guides/bearings which in your picture are the two brackets on either side that make the "T" slot. Scaled down versions can be found in vises or any lead screw based linear stage out there such as this one: [URL unfurl="true"]http://www.igus.com/wpck/16449/drylin_sht[/url]
I would call it a jacking screw, or a jackscrew, because that's pretty much what it does.
It jacks something into place, and holds it there once adjusted.
A leadscrew is usually a more dynamic device, i.e. it's typically used to move something continuously or regularly, and is rarely left in one position for long.
A leadscrew also, usually, exerts thrust in both directions (not simultaneously), whereas
a jackscrew, usually exerts thrust in just one direction, and gravity or strain resists the thrust.
Since you are presumably making the drawing, you could call it a leveling screw, or George, or whatever you want.
Remember to use two jack screws - The movement needs to be controlled in both directions. To adjust loosen one side 1/4 turn, tighten the opposite 1/4 turn to move the shaft or bearing or devise. Rinse, wash, and repeat.
