Ford Focus RS 2017 PH 8

Everything You Need To Know About Hydraulic Braking: The Parts Comprising Modern Brake Systems

When moving at 100km/h, your vehicle will need approximately the length of a football field to come to a full stop. That’s not a short distance by any means, but can you imagine how much longer it would take if your brakes aren’t in proper working condition? Drivers put little thought into their braking systems, whereas manufacturers make it a focal point of interest when designing cars. While the braking system is not flashy, it’s incredibly important to your safety on the road. For that reason, every new driver who hasn’t had to deal with braking problems should put in the effort to get familiar with all there is to them.

There are three ways to brake – using hydraulic brakes, engine braking and parking braking. Here, I’ll focus on hydraulic braking, which is the braking that results from pressing the brake pedal. The hydraulic brake system is comprised of a few different parts, some of which are considered consumables, meaning you’ll have to occasionally replace them as they’re designed to wear down with time and use.

Parts Of A Braking System

Brake Pedal

The brake pedal is what creates leverage, and is located on the left side in 2-pedal automatic vehicles, or the middle in 3-pedal manual vehicles. This is the first part that triggers the sequence of events that lead to the stopping of your vehicle. The brake light switch is connected to the pedal, so pressing the pedal will turn on the lights. The brake pedal seldom causes problems on its own, but it often reflects problems in the braking system or other braking parts. For instance, a spongy pedal can indicate brake fluid leaks or air in the brake lines. A vibrating pedal can indicate warped brake rotors.

Brake Booster

The brake booster helps amplify your foot power. After all, you’re stopping a tonne-heavy vehicle using just your foot. Brake boosters are incredible devices that amplify your foot power from the brake pedal by using the vacuum from the intake manifold plus the differences in air pressure, adding an extra punch into the master cylinder. There are several issues that can come from a failing brake booster, such as increased braking distance, a stiff brake pedal and a hissing noise.

Master Cylinder

The master cylinder is responsible for converting the kinetic energy that comes from the brake booster into hydraulic pressure. This is done by brake fluid going into the master cylinder, where the brake booster pushes the master cylinder piston to compress the brake fluid via the brake lines. As liquid isn’t compressible, pressure builds and is transferred to the braking mechanism at the wheels. The master cylinder generally features two cylinders that control two hydraulic circuits, each of which handles two of your four wheels. This is an added safety measure in case one of the hydraulic circuits fails. A failing master cylinder can leak brake fluid under the front of your vehicle, prevent the pedal from springing back into position, or make the car drift to one side while braking if a hydraulic circuit fails.

Brake Lines And Hoses

The brake lines and hoses transfer brake fluid and hydraulic pressure from the master cylinder to the disc brakes. Brake lines come in the form of rigid metal tubing that runs through the chassis, whereas brake hoses are flexible tubing that connects the rigid brake lines to the braking mechanism, where wheel movement occurs. Damage to either of these parts results in brake fluid leaks and uneven pressure to the wheels, causing your vehicle to pull to one side.

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Disc Brakes

Disc brakes feature brake rotors, calipers and brake pads. When you press the brake pedal, pressure through the brake fluid engages the caliper pistons, which causes the brake pads to squeeze on the brake rotor. The friction between the rotors and the pads is what actually stops the wheels. An alternative to disc brakes are drum brakes, but those are typically found on older vehicles.

Disc brakes come in an open design, making the dissipate heat more efficiently. They’re found on all wheels of your vehicle, or at least on the front two if you have an older vehicle with a disc/drum brake combination. This is due to the fact that the front wheels take on the majority of the braking force, and disc brakes are better at handling heat and have a faster braking response when compared to drum brakes.

Brake Rotors

These car parts are mounted on the wheel and spin alongside it. Brake rotors are generally made of cast iron, steel or carbon-ceramic, and can come in either drilled or slotted designs for better heat dissipation. Over time, the rotor’s surface can wear down from contact with the brake pads, and since its thickness plays a huge role in its performance and your safety, you should always change them during routine brake pad changes. Problems associated with worn down or damaged rotors include the cause of vibrations in the steering wheel and brake pedal when braking; loud grinding noises and cracks in the rotor from repeated stress and high temperatures.

Brake Calipers

These parts are mounted over the rotor, feature pistons, and hold the brake pads on either side of the rotors. They’re available in one of two designs – floating calipers, which feature pistons on one side, or fixed calipers, which feature pistons on both sides. Worn down or damaged brake calipers can cause the car to pull to one side as the brake pad is still applied on one wheel, or leakage of brake fluid, resulting in decreased braking power.

Brake Pads

Car brake pads are mounted on the calipers, and they have a friction material that faces the rotor. Car brake pads are available in different materials that provide different levels of stopping power, brake dust production and longevity. With use, the friction material wears down, and you shouldn’t allow it to be less than 0.5cm thick before replacing the pads. If that happens, you may experience squealing noise, the rotor can be damaged, and the vehicle can veer to one side.

Drum Brakes

As aforementioned, drum brakes are the older type and come in an enclosed design. While they’re more complex than disc brakes, they’re more affordable to replace. Moreover, they make it easier to install parking brakes in them, which is why you can still find them on some economy vehicles. Due to their closed design, they overheat more and have the tendency to brake fade.

Brake Drum

The brake drum is fixated to the wheel hub and rotates with it. The drum is typically made of iron, making it wear-resistant. Some of the issues that can occur with a brake drum are drum expansion due to excess heat, which results in a wider gap between the drum’s inner surface and brake shoes, leading to something known as long pedal, where you have to press the pedal further down to start braking; water ingress tendency, where the water has no place to go until it evaporates from the heat, negatively impacting brake performance, and excessive drum wear causing the wheel cylinder piston to slip out of its bore.

Wheel Cylinder

The wheel cylinder can be found inside the brake drum and is mounted to the top of the backing plates. Wheel cylinders generally feature two pistons that are attached to the brake shoes and push them outwards. A faulty wheel cylinder can get the piston stuck from corrosion, and result in brake fluid leakage.

Brake Shoes

These curved metal pieces have a friction lining on one side and are mounted inside the brake drum with the friction lining facing towards the drum’s inner surface. Their function is similar to that of brake pads, so they also come in a range of materials. Symptoms of worn brake shoes are grinding noises, rattling sounds and a less effective parking brake.

The Final Word

Proper driving practices involve gauging enough braking distance, avoiding tailgating and pressing the pedal gently. minimising rash brake use can prolong the lifespan of your brake parts, and improve fuel economy. Worth noting is that regular brake inspection and service can help you spread out the costs associated with repairs and replacement parts.

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