the track bar does not move straight up and down, it moves along a radius with the axis being the axle mounting point.
So as you lift the Jeep, you change the radius and as the track bar wants to "center" at it's axis (the axle mounting point) it'll seem to shift to one side or the other depending on which direction it's traveling on the axis.
Here's a simple way you can see what it does, take 3 pencils of equal length, lay them length wise on a flat surface one above the other like so:
--------------------
--------------------
--------------------
Now take a rubber band and wrap it about an inch in from the left side of the middle and bottom pencil
Take another rubber band and wrap it about an inch in from the right side of the middle and top pencil
holding the bottom pencil still, lift the top pencil and you will see it shift more to one side. this is what the track bar does as you lift your Jeep.
Hope it helps! now I need :beer::beer::beer: for all that thinking on a Saturday night :crazyeyes: