【正文】
ng failure can be result in serious consequences. The main part of the braking system is the brake. In the modern car brake shoe brake drum which has high braking efficiency is still widely used.Drum brake, also known as blocktype brake. The mainstream of drum brakes is sheets style, and its brake shoes located inside the brake wheel. When braking, brakeblocks open outward to friction the inside of the brake drum. The design of the friction drum brakes were related to the design and calculati