Remove the cotter pin from the ball joint stud and loosen the locknut three or four turns, but do not remove it completely.
Remove the cotter pin and locknut from the opposite ball joint stud.
Choose the appropriate pressure bolt and put the tool between the ball joint studs, centering the bolt against the stud to be removed.
Turn the locknut so there is a gap between it and the knuckle body in order to separate the ball joint. If the locknut is against the knuckle body, the ball joint cannot separate.
Hold the tool body; tighten the pressure bolt against the ball joint stud.
Strike the control arm sharply with a plastic mallet until the ball joint stud is separated from the knuckle body. You may have to make several attempts to separate the ball joint stud.
Remove the tool and locknut, turn the tool over, and repeat the above steps for separating another ball joint stud.