When the wheel brake is working, most of the heat generated by friction with the ground is transferred to the brake drum, which causes its temperature to rise. When the brake drum heats up, it will expand and increase the brake clearance. In order to reduce the temperature rise, the brake drum should have a large thermal capacity, so the brake drums have a sufficient mass. Some cars also cast a number of ribs on the outer surface of the brake drum to increase heat dissipation area and stiffness.
???? The friction plate has poor thermal conductivity, and the heat transmitted to the brake shoe through it is very small, and it is difficult to dissipate heat to the atmosphere. Therefore, the temperature of the working surface of the friction plate will also be very serious. When the temperature of the friction plate is too high, it will cause the friction coefficient to decrease greatly and seriously affect the braking performance. This phenomenon is called the thermal decay of the brake. In addition, the wear resistance will be deteriorated and the service life will be shortened. In severe cases, the friction plate will be burned. Therefore, the material formula and manufacturing process of the friction plate must ensure that the friction plate has good thermal stability.