Auto Braking Systems Safety and Maintenance
"Don't drive with the emergency brake on and when you push the pedal and the car coming to a stop, beyond that I don't know anything about my cars brakes."
Sound familiar? Don't worry, your car's braking system is not really all that complicated. The follow guide will help you understand what the basic components are and what actually happens when you apply your car's brakes.
Basic Components:
The brake pedal presses on a small cylinder mounted on the firewall. This is called the master cylinder. The master cylinder compresses brake fluid throughout the brake line which in turn pushes on a larger cylinder at each wheel. The wheel cylinder then press on brake pads which clamp a rotating disk in a disk brake system or press on a rotating drum in a drum brake system. The disk or turn is mounted directly to the axles with the same wheel studs that hold the wheel and tire on the axle. A more in depth explanation with illustrations can be found atFamilycar
How brakes work:
Modern automotive brakes are very reliable because they are relatively simple systems. Though simple in nature, this is a very powerful system because of the amount of kinetic energy (momentum) that is converted into thermal energy (heat) each time your car stops. The extreme force required of a car's brakes comes about due to harnessing hydraulic principles. Essentially a small piston acting over a long stroke (brake pedal and master cylinder) pressurizes oil (brake fluid) so that a larger piston can move over a smaller stroke (brakes on each wheel) with a much greater force. At the highest point in the system, generally mounted on the vehicle's firewall, is a brake fluid reservoir which supplies the system with extra fluid as needed. Follow this link for more information about howhydraulicmachines work.
Maintenance:
Since automotive braking systems are so simple, they require very little maintenance for the amount of work they perform. As the brake pads or shoes wear their friction material is used up and they must be replaced. Since these are "consumable" components they are designed to be replaced relatively easily. Brake fluid is hygroscopic meaning it will actually absorb moisture from its surroundings. For this reason, it is recommending to change your brake fluid periodically to prevent moisture build up in the lines.
The biggest maintenance concern is air in the brake line. Since air is not as dense as hydraulic fluid it will compress and therefore brake pressure will not be fully transferred from the brake pedal to the brake pads. To remedy this, the air is "bled" out of the brake lines by putting pressure on one end (via the brake pedal) and opening the other end allowing all the air to escape. This can be a messy process that requires two people. "Speed bleeders" can be used to make life easier. These are essentially check-valves that once opened will allow air and fluid to escape the brake line once pressure is applied. After all of the air is out of the line, the bleeder is closed and the system is air-free and ready to work.
Safety:
Modern braking system are very reliable however problems do occur. If you find yourself careening down the road and your brake fail, first pump your brake pedal several times. Chances are you have a leak or air in your hydraulic brake line. By temporarily over pressurizing the system with several hard pumps on the pedal, you can often overcome the leak and bring your car to a safe stop. If this does not work, try using the emergency brake. This will be very hard to modulate and will most likely just lock itself down hard against the wheels. The result will be a fairly aggressive but relatively safe stop. Once you have safely stopped, count your blessings and get your car to a certified automotive technician right away so they can make proper repairs.
Modern automotive brakes are truly engineering marvels. They provide an extremely powerful force consistently for thousands of miles while requiring little maintenance. The fact that they perform this work using very few moving parts and very little total weight is even more remarkable. Next time you are driving, stop and think how impressive that is
