The appearance of brake drum look like the drum of iron castings,on the surface of the brake drum,has 4 grooves.

    There many advantage of the grooves as follow:

    1,it can overcome skid which soaked by the water or oil.

    2,the grooves can improve the heat dissipation potention.

    3,interdict the surface crack extention.

    4,increase the brake drum life.

    5.prevent the brake drum deformation.