(Editor’s Note: In past articles, we’ve discussed the importance of replacing brake clips and changing brake fluid, but today we want to look at the big picture, how brakes work – a brief guide to brake systems. Enjoy!)
Sooner or later it happens. You take your eye off the road for a second and when you look up, you see that traffic has come to a standstill. Instinctively, you slam your foot on the brake pedal.
Whether you stop in time and breathe a sigh of relief or hit the car in front of you, the mechanics of deceleration and stopping are the same.
How Brakes Work
Recall the last time you slammed on your brakes. Ever wonder how your foot stopped thousands of pounds of moving metal?
“It all goes back to high school physics.”
It all goes back to high school physics. In order to stop the car, your brakes use a system of fluid-filled pipes that multiply the force of your foot pushing on the pedal and then transmit the force to the wheels of the car.
As shown above, fluid multiplies the force of you foot many times over.
We’ll see below how brake fluid transfers the force of your foot through the tubes and hoses to the wheels. Because it circulates through the brake system like blood through your body, it has to be clean to be effective. For more on the importance of changing brake fluid and signs yours may be dirty, click here.
When you press on the brake pedal, your foot moves a lever that forces a piston into a long, narrow cylinder filled with brake fluid. As the piston pushes into the master cylinder, brake fluid shoots through the brake lines to the calipers and much wider wheel cylinders next to each of the four brakes.
The wheel cylinders contain pistons connecting to a disc brake pad or brake shoe. Because of the laws of physics, the force you apply when you step on the pedal is multiplied exponentially and allows the disc brake pad or brake shoe to apply enough friction against the surface or wall of the brake drum to slow the rotation of the tire.
Once you take your foot off the pedal, the pads and shoes are released, sending the brake fluid back to the master cylinder.
There are two common types of brakes.
How Brakes Work: Disc Brake Systems
Disc brake systems are standard on the front wheels and consist of a disc or rotor, a caliper assembly, disc brake pads and their hardware, and the wheel bearings. As noted above, brake fluid is delivered from the master cylinder to the caliper through tubes, hoses, and valves.
How Brakes Work: Drum Brake Systems
Many cars have the less expensive drum brakes on the rear wheels. Drum brake systems consists of a drum and backing plate, a hub or axle assembly, brake shoes and hardware, the wheel cylinder, and wheel bearings. Like disc brakes on the front wheels, tubes and hoses allow the brake fluid to flow from the master cylinder to the wheel cylinders in back.
Brake systems are the most important safety feature on a car or truck. If you experience problems – squeaky brakes, pulling to one side, a hard or soft brake pedal, a grinding noise or more– it’s imperative to diagnose and fix the problem. That way, when you slam the brake pedal to the floor, all the components in the brake system do what they’re supposed to and stop the car.