What is primarily used in a disc brake system to stop the vehicle?

In a disc brake system, the primary component used to stop the vehicle is the brake pads. When you apply the brakes, hydraulic pressure forces the brake caliper to compress the pads against the spinning disc (or rotor). This friction between the pads and the rotor is what ultimately slows down and stops the vehicle. The material of the pads is specifically designed to create a strong frictional grip while also being durable enough to withstand high temperatures generated during braking.

The other components, such as brake shoes, drums, and fluids, are parts of different braking systems or play supporting roles but do not function as the primary element responsible for halting motion in a disc brake system. Brake shoes and drums are characteristic of drum brake systems. Brake fluid is essential for transferring the hydraulic force from the brake pedal to the calipers but does not engage directly in the braking process itself.