A Crash Course on Your Vehicle's Braking System
Friday, August 20, 2010
Your car's brake system is the result of decades of improvements. Its performance is dependent on the seamless execution of several tasks, which are handled by your master cylinder, rotors, calipers, and pads. A failure with any of those parts can lead to disastrous consequences.
When you need to stop your vehicle, you press down on your brake pedal, expecting your car to come to a full stop. What happens next is a mystery to most drivers. The pedal creates pressure within your master cylinder. That, in turn, pushes brake fluid through a network of hoses that lead to each of your tires. Calipers and pads at each tire apply pressure to the rotors and thereby, stop your vehicle.
Below, we'll take a tour through this entire system. I'll explain each of the parts involved in more detail, so you'll understand the process by which your brakes stop your car. I'll also describe a few common problems that you may eventually confront.
The Role Of Your Master Cylinder
Your car's master cylinder is located in front of the driver's seat. It is actually comprised of two individual master cylinders; each one controls the braking units of two wheels. The design is a fail-safe feature. If one of the two sides fails (though such an event is rare), the other side ensures you will still be able to stop your vehicle.
When problems occur, they are usually due to leaks that have formed somewhere in the brake line. A leak will cause the pedal to drop to the floor when your foot is pressing down on it.
The Purpose Of Brake Fluid
Braking fluid allows the entire system to work effectively. The fluid is formulated to withstand low and high temperatures so it avoids congealing or boiling (respectively). As noted above, it flows from the master cylinder through the brake line to the wheels.
You'll find a reservoir in which you can replenish the fluid located on top of the master cylinder. You should be able to determine how much is in the reservoir without removing the cap. If you notice the level dropping below the two-thirds marker, have a mechanic check the braking system. Worn pads can often cause the level to decline.
Basic Construction
Disk braking systems have largely replaced drum brakes. They're more durable and last longer than drums. Moreover, they are less susceptible to water and more effective for stopping your car. The assembly consists of pads, rotors, and calipers.
Each caliper has a pair of pads. The pads are fastened on either side of the rotor. When you press the brake pedal to stop your car, the caliper places pressure on the pads, which squeeze around the rotor. The friction brings your vehicle to a stop.
Over time, the pads wear down and must be replaced. The rotor likewise suffers wear and tear by developing grooves from the pressure placed upon it by the pads. When grooves appear, the rotor needs to be machined to make its surface smooth enough to provide the necessary friction for stopping. Rotors can only be machined to a certain point before they become unstable. Once that point has been reached, they must be replaced.
Common Problems
Your braking system can develop a number of different problems. Some are serious and need immediate attention while others can take a lower priority (for awhile). Squealing is one of the most common problems people experience. It is typically caused by vibrations between the pads and calipers. Replacing the former and machining the latter usually resolves the problem.
Other issues include pulling to one side when your brakes are engaged, a "grabbing" sensation, and pulsation. As noted, you might also experience a drop in the pedal when leaks form, or a pedal that feels spongy.
Any problem you experience with your vehicle's braking system should be inspected by a mechanic as soon as possible. Even low-priority issues (e.g. squealing) can worsen to the point that they become more expensive to resolve.
When you need to stop your vehicle, you press down on your brake pedal, expecting your car to come to a full stop. What happens next is a mystery to most drivers. The pedal creates pressure within your master cylinder. That, in turn, pushes brake fluid through a network of hoses that lead to each of your tires. Calipers and pads at each tire apply pressure to the rotors and thereby, stop your vehicle.
Below, we'll take a tour through this entire system. I'll explain each of the parts involved in more detail, so you'll understand the process by which your brakes stop your car. I'll also describe a few common problems that you may eventually confront.
The Role Of Your Master Cylinder
Your car's master cylinder is located in front of the driver's seat. It is actually comprised of two individual master cylinders; each one controls the braking units of two wheels. The design is a fail-safe feature. If one of the two sides fails (though such an event is rare), the other side ensures you will still be able to stop your vehicle.
When problems occur, they are usually due to leaks that have formed somewhere in the brake line. A leak will cause the pedal to drop to the floor when your foot is pressing down on it.
The Purpose Of Brake Fluid
Braking fluid allows the entire system to work effectively. The fluid is formulated to withstand low and high temperatures so it avoids congealing or boiling (respectively). As noted above, it flows from the master cylinder through the brake line to the wheels.
You'll find a reservoir in which you can replenish the fluid located on top of the master cylinder. You should be able to determine how much is in the reservoir without removing the cap. If you notice the level dropping below the two-thirds marker, have a mechanic check the braking system. Worn pads can often cause the level to decline.
Basic Construction
Disk braking systems have largely replaced drum brakes. They're more durable and last longer than drums. Moreover, they are less susceptible to water and more effective for stopping your car. The assembly consists of pads, rotors, and calipers.
Each caliper has a pair of pads. The pads are fastened on either side of the rotor. When you press the brake pedal to stop your car, the caliper places pressure on the pads, which squeeze around the rotor. The friction brings your vehicle to a stop.
Over time, the pads wear down and must be replaced. The rotor likewise suffers wear and tear by developing grooves from the pressure placed upon it by the pads. When grooves appear, the rotor needs to be machined to make its surface smooth enough to provide the necessary friction for stopping. Rotors can only be machined to a certain point before they become unstable. Once that point has been reached, they must be replaced.
Common Problems
Your braking system can develop a number of different problems. Some are serious and need immediate attention while others can take a lower priority (for awhile). Squealing is one of the most common problems people experience. It is typically caused by vibrations between the pads and calipers. Replacing the former and machining the latter usually resolves the problem.
Other issues include pulling to one side when your brakes are engaged, a "grabbing" sensation, and pulsation. As noted, you might also experience a drop in the pedal when leaks form, or a pedal that feels spongy.
Any problem you experience with your vehicle's braking system should be inspected by a mechanic as soon as possible. Even low-priority issues (e.g. squealing) can worsen to the point that they become more expensive to resolve.
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