Thanks for the reply! I understand what the piston tutorial is getting at, but the book wants me to solve the problem using IK and joints. I've made SOME progress since I made this post, though: Now, the arm's front end stays "glued" to the pump part, like it should, and the arms move with the wheels, but their movement is way off . . . if I turn the center wheel (the parent of the joints), the arms move correctly, but they move way outside the range they should be moving in. I tried using Constraints on them, but Maya tells me that the "list of targets" is empty and errors out. What do I need to do differently here? I've attached a couple of screenshots to show how I've got it working thus far . . . see how when the wheel is at zero degrees rotation, the armature assembly is where it is supposed to be. But, when i rotate the wheel 100 degrees, the arm flies way up above the wheel, and then back around behind it, etc., moving to the exact same degree as the wheel is, but needing to be "confined" somehow to just moving up and down, in and out on the wheels. Any ideas?