Types of Brake
Types of Brake The two main types of friction brake are drum brake and disc brake (Fig. 28.4). In both types a fixed (non-rotating) shoe or pad rubs against a moving drum or disc. To increase the friction between the rubbing surfaces, a special friction material is attached to the fixed part. Earlier this friction material had a high content of asbestos, but its dust is injurious to health so that a safe asbestos free friction material is nowadays used. Fig. 28.4. Types of brake. Drum Brakes. This internal expanding type of brake contains two shoes that are attached to a back-plate and are fixed to a stub axle or axle tube. The section of each shoe is of "T" shape. A friction lining is riveted or bonded to the outer face of the shoe. A drive is fitted at one end of the shoe so that the shoe expands when the brake pedal is applied. In a simple brake (Fig. 28.5) a cam is used as a shoe expander, but modern systems for cars use hydraulically operated pistons for shoe expansion.