The drum surface that friction pads contact should be made of which material?

The drum surface that friction pads contact should be made of which material?

• A. Cast iron or aluminum.
• B. Stainless steel
• C. Plastic
• D. Brass

Answer: (A)

The surface that the friction pads contact must hold up under repeated, high-temperature friction and wear. It needs to be hard enough to resist gouging and to maintain a smooth, true running surface so the shoes can bite evenly. Cast iron has been the traditional choice because it handles braking heat well, resists wear, and can be machined to a precise, flat surface that doesn’t distort easily under heat. Aluminum is used in some lighter-weight drum designs, offering reduced weight and good heat dissipation while still providing a suitable surface for the friction material when the design accounts for wear and temperature. Stainless steel tends to wear differently and can be more prone to galling or glazing with friction materials, while plastic or brass would wear too quickly or deform under braking temperatures. So the drum surface is typically cast iron, with aluminum as an alternative in specific designs.

The surface that the friction pads contact must hold up under repeated, high-temperature friction and wear. It needs to be hard enough to resist gouging and to maintain a smooth, true running surface so the shoes can bite evenly.

Cast iron has been the traditional choice because it handles braking heat well, resists wear, and can be machined to a precise, flat surface that doesn’t distort easily under heat. Aluminum is used in some lighter-weight drum designs, offering reduced weight and good heat dissipation while still providing a suitable surface for the friction material when the design accounts for wear and temperature.

Stainless steel tends to wear differently and can be more prone to galling or glazing with friction materials, while plastic or brass would wear too quickly or deform under braking temperatures. So the drum surface is typically cast iron, with aluminum as an alternative in specific designs.