I'm doing some calculations on a set of drumbrakes. In a book I have from my school days it says that the normal force on each shoe are not equal (this is the force appearing on the outer left and right sides of the drum when viewing the drum from the side). This apparently leads to different amounts of wear on each shoe. I can't figure out why they shouldn't be equal, so if someone can explain it to me I'd be greatful. Also, if someone could explain why a band brake works better in one direction than the other that would be real nice.