If the brake drum is not designed properly, it will change easily when heated; if the force of the brake drum is unbalanced, it will also produce mechanical deformation, make the shoe and drum in bad contact, resulting in the increase of pedal force and stroke; if the working surface of the brake drum is too large, it will cause self-locking, vibration and noise. Therefore, the brake drum should have sufficient wall thickness and cast circumferential or axial stiffeners on the outer surface near the opening to improve the strength. These stiffeners also play the role of heat dissipation, which can reduce the friction surface temperature, shorten the brake cooling time, and increase the energy capacity by 35% ~ 40%.
The working surface of the brake drum is generally finished by positioning the bearing hole after assembly with the hub. The tolerance of roundness and coaxiality of working face of minicar is required to be ≤ 0.03mm, radial run out ≤ 0.05mm, static unbalance ≤ 1.5n · cm.