What is the difference between brake shoes and brake pads?

Brake shoes and brake pads are both components used in different types of braking systems, but they differ in terms of their design, function, and application. Here are the main differences between brake shoes and brake pads:

1. Design and Construction: Brake shoes are used in drum brake systems, while brake pads are used in disc brake systems. Brake shoes are curved metal plates that are lined with friction material on the outside surface. They are designed to press against the inner surface of a brake drum. Brake pads, on the other hand, are flat or slightly curved plates that are installed in a caliper and make direct contact with the brake rotor.

2. Friction Material: Brake shoes and brake pads use different types of friction materials. Brake shoes traditionally used asbestos-based materials, but these have been largely phased out due to health concerns. Nowadays, brake shoes are typically lined with friction materials made of non-asbestos organic compounds or semi-metallic compounds. Brake pads, on the other hand, commonly use semi-metallic, ceramic, or organic friction materials.

3. Braking Mechanism: Brake shoes work on the principle of expanding against the inner surface of the brake drum. When the brakes are applied, hydraulic pressure or mechanical force pushes the shoes outward, pressing them against the drum to create friction and slow down the rotation. Brake pads, in contrast, operate by squeezing against the rotor. When hydraulic pressure is applied to the caliper, the pads are pushed against the rotor, generating friction and decelerating the wheel.

4. Heat Dissipation: Brake pads typically have better heat dissipation capabilities compared to brake shoes. The design of disc brake systems allows for improved airflow around the brake rotor, aiding in heat dissipation. This makes disc brakes more effective in dissipating heat generated during braking, reducing the risk of brake fade.

5. Performance: Disc brakes with brake pads generally provide better braking performance compared to drum brakes with brake shoes. Disc brakes offer more consistent and responsive braking, particularly in high-demand situations or during heavy braking. They tend to provide shorter stopping distances, better modulation, and superior overall performance.

It's important to note that the choice between brake shoes and brake pads depends on the specific braking system used in a vehicle. While drum brakes with brake shoes are still employed in certain applications, disc brakes with brake pads have become the standard for most modern vehicles due to their improved performance and reliability.