Your car’s braking system is an ingenious way by which to bring a very heavy vehicle to a safe stop. This design, though very efficient, is actually quite old and has withstood the test of time. Let’s take a look at parts of the braking system in today’s cars and discover what exactly about their design gives you, or even your grandmother, the ability to slow and stop a fast-moving car.
First, let’s talk about basic hydraulics. Pascal’s principle is the main idea behind the use of hydraulic brakes. This principle states that if you apply a force to an enclosed fluid, that force will be transmitted undiminished throughout the entirety of the fluid and to the walls surrounding that fluid. So, when grandmother presses her small foot on the brake pedal, she applies a small force to that pedal. Fifty years ago, she would have had to press much harder to make the brakes contact the wheels, but today we have power braking thanks to a part of the system known as the master brake cylinder. This cylinder amplifies the power applied by your wonderful old grandmother and allows her to stop the metal behemoth quickly.
The small force applied to the brake pedal is transmitted from a small cylinder at the back of the pedal and into the brake line. Amplification of the force takes place in the master brake cylinder and the fluid is pressurized along the length of the brake lines to the individual wheel brake cylinders. Most cars have at least one brake cylinder at each wheel, but some produced today will have two per wheel to decrease uneven brake wear. This cylinder presses the brake pads against the brake disc and through the use of friction slows the car down.
If at any point there is a loss of fluid or a cylinder ceases proper function, there can be a loss of braking power. In the engine compartment there is a brake fluid reservoir that holds some extra fluid in the event of a small leak. The level of fluid in the reservoir should be checked occasionally to ensure that the car will continue to have the fluid necessary to extend the cylinders on the wheel callipers. However, if too much fluid is lost, the system may be able to compensate with another fluid; air. If you have found your brakes have failed, try pumping them continually until you notice resistance in the pedal. This “gulping” of air acts as a temporary brake fluid and may work long enough to help stop the car. Then have your vehicle checked immediately by a qualified mechanic.