Gary, my young son...let me explain to you the facts of life....
...yes, the dust cap just pulls straight off! However, that sucker is tight! So, you take that long head nut & screw it onto the stud on the end of the cap...then, you put a long bolt in the other end of the nut (or, if you've made a trick tool like me, screw it in) that protrudes out of the hub...if you can figure out a way to hammer it out, go for it...me, I'd just put a ratchet on that extension & start "loosening"....true, there's no threads to 'loosen' but the process of turning the cap backs it up a bit so its free from all the grease, etc holding it in to where you can then pull it straight out....also, I believe the inner race of the hub is angled just a bit to snug the cap into itself....
....oh, I've seen caps where somebody 'hammered' on them to get them out...did you know they rip easily? &, that stud will pull right out of them!