By adding the gears it would create the look that the arms and legs are rotated by gears that are attached to the engine in the torso(I just put a box but detail could be added to make it look like an engine). With these I think it would look more powerful but if you were going for the I-Robot look then I would make the engine the same texture as the head,torso,thighs,etc. and not add detail to it(so it looked like my example). If you don't like the look of it then thats fine but I thought that I would give you a visual refrence of my idea.
-edit-: P.S. I needed to try my hand at some more photoshop anyway!
