This ^^ is correct. The pins will have a groove in them. This groove should be facing the headstock, and will slide down the string, past the ball-end. When under tension, the ball-end will not be beneath the pin, but alongside, such that the more tension, the more the string itself tightens the pin against the hole. If done properly, the pin cannot come out, however high the tension. The bridge would bust first.
Hope this helps.