How Brakes Work

The layout of a typical brake system. See more pictures of brakes.

Next Up

• Braking Guide
• How Emergency Brakes Work
• How Disc Brakes Work
• Brake Type Differences Quiz

We all know that pushing down on the brake pedal slows a car to a stop. But how does this happen? How does your car transmit the force from your leg to its wheels? How does it multiply the force so that it is enough to stop something as big as a car?

When you depress your brake pedal, your car transmits the force from your foot to its brakes through a fluid. Since the actual brakes require a much greater force than you could apply with your leg, your car must also multiply the force of your foot. It does this in two ways:

• Mechanical advantage (leverage)
• Hydraulic force multiplication

­The brakes transmit the force to the tires using friction, and the tires transmit that force to the road using friction also. Before we begin our discussion on the components of the brake system, we'll cover these three principles:

• Leverage
• Hydraulics
• Friction

We'll discuss leverage and hydraulics in the next section.