the jack isn't ment to push a tree that's severly leaning back, it is mearly to give the tree a little push to get it to go over. many contractors around here use them, because it's not real practial to have to drive a bar, hook up a cable and come-a-long every time you fell a tree.
the best way, is to get the jack so it's base sits on a root, then the top ear bites into the sap wood, and your good to go, we take a little strain on the tree, then make our back cut, remove the saw, and give it a couple jacks. if the tree isn't going to go over, then we'll make room and push it with our skidder, but for most trees, the jack works great. in fact, we mounted ours right on the side of the skidder, so it's easier to carry in the woods.
