Automotive braking systems


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Automotive braking systems

  1. 1. Figure 1 Donald E Maurer
  2. 2.  Your driving a car or truck. You press on the brake pedal, what happens?  A vehicle car goes through a process that multiplies the force you apply to the brake pedal with your foot and leg to stop the car.  This force is transmitted to the road through a series of parts using fluid pressure in most of today’s vehicles.
  3. 3.  THE BRAKE PEDAL  There are two or three pedals in today’s vehicles.  The pedal in the middle, or the pedal that is immediately left of the gas pedal is the brake pedal.  The main purpose of the brake pedal is to multiply the force that is exerted by the driver to slow and stop the vehicle.
  4. 4.  BRAKE BOOSTER  Brake boosters are only used with power braking systems. This is standard on today’s vehicles.  The booster is used to provide more braking power while reducing the required effort from the driver.  Booster’s usually operate by using the vacuum from the vehicle engine.  Not all vehicles have this type of booster. Some provide assistance electrically.  Not all vehicles will have a booster. Some will be direct pressure from the driver.
  5. 5. Figure 2 8p83QqGmGhyjxN-0yZAZEB487
  6. 6.  MASTER CYLINDER  A master cylinder is provided to convert force from the booster into hydraulic pressure.  If the vehicle does not have a booster the pressure is converted from the brake pedal.  It is easier to transfer hydraulic pressure than mechanical pressure to Figure 3 the brakes.
  7. 7.  BRAKE FLUID, LINES, AND HOSES  Fluid pressure travels from the master cylinder through the brake lines to the brakes at each wheel of the vehicle.  Brake lines are rigid except at the wheels where it is necessary to provide flexibility because of the movement of the suspension.  The rigid lines are either steel or a composite material that can withstand the corrosive environment under the vehicle.  Part of the line is steel while a short flexible material (reinforced rubber) is used to connect it to the moving parts.
  8. 8.  Brake fluid must withstand extreme pressure and temperature changes. It’s VERY important that the fluid:  Cannot be compressed  Has a very high boiling point and flash point  Will not cause corrosion on the inside of brake lines  Can withstand extreme cold without thickening
  9. 9. Figure 4 disc_brake_diagram.jpg/619px-Hydraylic_disc_brake_diagram.jpg
  10. 10.  BRAKE CALIPERS  Fluid must be converted from hydraulic pressure to mechanical pressure.  Calipers contain a piston/s that convert hydraulic fluid pressure back to mechanical pressure.  A bigger piston or multiple pistons will produce more force.  Racing or high performance applications will use 4 or even 6 pistons in the caliper.  Calipers are used with disk brake systems.
  11. 11.  BRAKE PADS  Brake pads are forced against the rotor by pressure applied from the caliper.  Friction from the contact between the pad and rotor slows the speed of the rotor.  This friction produces heat.
  12. 12.  BRAKE ROTORS  The rotor is acted upon by the brake pads.  The friction produced is converted into torque at the wheel.  Rotors must be able to dissipate heat.  Many rotors are made with cooling fins that help to quickly dissipate heat.  Rule of thumb – the bigger the rotor is, the better it is at reducing heat, the better the stopping power of the brakes.
  13. 13. Figure 5
  14. 14.  WHEELS AND TIRES  The wheels and tires provide the contact between the vehicle and the road.  The primary function is to provide traction.  Traction works three ways:  Increased acceleration.  Shortened stopping distance.  Increased cornering or handling.
  15. 15. Figure 6 xlR5Jew6lFRqjjj1OIIKeiL6AImSn3GXldjLlHGd
  16. 16.  The brake system is designed to increase the pressure you apply to the brake pedal. The increased pressure is applied to the calipers through hydraulics. The calipers convert the hydraulic pressure back to mechanical force against the rotors. The rotors apply torque to the wheels. The wheels and tires provide traction to stop the vehicle.
  17. 17.  Erjavec, J (2010).Automotive Technology: A Systems Approach. Clifton Park, NY: Delmar, Cengage Learning. (p1424-1456) Inline Citation -- (Erjavec, 2010)
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