They set up two classes of stock--a large block of nonvoting Class A stock (which was willed to the charitable Ford Foundation) and a much smaller block of Class B stock that had voting rights (and was willed to the family).
In the mid 1930s, Henry Ford and his son, Edsel, set up the two-class structure as part of their estate planning: the charitable Ford Foundation received most of the shares, but they kept a small block of Class B shares that had voting rights, thus assuring family control.