How Brakes Work

By Bill Stephens,2014-11-08 22:07
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How Brakes Work

    How Brakes Work by Karim Nice

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    Nice, Karim. "How Brakes Work" 16 August 2000.


    m> 28 August 2010.

    Inside this Article

    1. Introduction to How Brakes Work

    2. Leverage and Hydraulics

    3. Friction

    4. A Simple Brake System

    5. Lots More Information

    6. See all Brake Types articles

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    Brake Image Gallery

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

    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

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    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:




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

Leverage and Hydraulics

    In the figure below, a force F is being applied to the left end of the lever. The left end of the lever is twice as long (2X) as the right end (X). Therefore, on the right end of the lever a force of 2F is available, but it acts through half of the distance (Y) that the left end moves (2Y).