Re: A racheting type animation---

the easiest way is to orient constrain the rachet bit to the bolt object. That when when you rotate the bolt the ratchet bit rotates with it, then when the handle is swung back the head doesn't seem to move with the handle because it is actually only rotating with the bolt.

Another way is to use a semi-advanced expression that only rotates the head when the handle(or parent) is rotating in the proper direction. the problem with this is it requires knowledge of the frame before, effectively turning this into more of a simulation than direct animation.