How Disc Brakes Work
Disc brakes make a crucial part of a brake system and utilise the force applied on the wheel discs to slow as well as stop a car. A disc brake is preferred over drum brakes for its superior performance and higher resistance to overheating. While there are still a few vehicles with drum brakes on the rear wheels, the front wheels of all vehicles use disc brakes. Moreover, there are quite a few cars, from trucks to family sedans and SUVs with four-wheel disc brakes.
Let’s find out all about the components and working of a disc brake.
Disc Brake System Components
To understand the functioning of a disc brake system, you must first understand its different parts:
1. Rotor or the Brake Disc
Rotor is a disc, mounted on the wheel hub and rotates with the wheel. These are mostly made up of steel or cast iron. However, you will find carbon-ceramic rotors in some high-end vehicles as well. The braking process generates a lot of heat due to the friction between the disc and the pad. Therefore, most cars have ventilated discs for efficient heat dissipation on the front wheels. Some heavy vehicles have slotted rotors for the rear wheels as well. However, you may find some smaller vehicles with solid discs.
2. Brake Pads
Brake pads are responsible for pushing into the rotors and creating enough friction to stop or slow down a car. These pads have a metal part called a shoe from which a lining emerges that is in contact with the rotor and eventually wears away with time and usage.
This lining can be made of different materials; mainly organic, ceramic and semi-metallic. The nature and quality of the material determine how quickly the car stops after pressing the brakes, how much noise the braking process makes and how long the brakes will last.
3. Piston
This piston is a cylinder connected to the hydraulics of the disc brake system. When a driver applies the brake pedal, this piston is responsible for pushing the brake pads into the rotors. In some brake systems, there is only a single piston moving both disc pads but others have two pistons pushing the pads from either side of the rotor. Some more complex and expensive brake systems have 4, 6 or even 8 pistons. This ensures immediate and effective braking.
4. Caliper
The caliper is the part that covers the rotor and holds the pistons and the rotors. Disc brake calipers are of two types: sliding aka floating and fixed.
Floating calipers have pistons on only one side and these calipers slide over the rotor. When you press the brake pads into the rotor on one side during the braking process, the floating caliper slides over allowing the brake pads on the non-piston side to also come in contact with the rotor.
On the other hand, fixed calipers have pistons on both sides and are fixed in place. These calipers apply even pressure on the rotor and clamp more firmly. This is useful for heavy vehicles or strenuous driving as in sports cars but floating calipers are perfectly fine for everyday driving.
5. Sensors
In some modern cars, the brake system has sensors in the brake pads. This informs the driver if the disc pads are worn out and in some cases, these sensors are involved in the ABS system of the vehicle.
The Working of Car Disc Brakes
Now that you know about the disc brake parts, it would be simple to understand its functioning. Here is what happens when a driver presses the brake pedals:
- The piston in the master cylinder forces the hydraulic fluid into the brake lining, further moving the pistons and pushing the pads into the rotor.
- The higher the force on the pedal, the more will be the pressure in the car brake lines resulting in a more forceful squeeze on the rotor.
- The greater squeeze on the rotor, the quicker will the car stop or slow down.
- The pads only move a few millimetres and retract back to the calliper the moment the driver let go of the pedals.
- The friction between the rotor and the brake pad is quite a lot and releases the car’s kinetic energy in the form of heat.
- Moreover, as you apply the brakes, the friction also result in a noise characteristic of a car slowing down or stopping.
Disc Brake System Wear and Tear
To ensure your car’s brake system is working properly, you must keep the wear and tear on the following components in check and repair or change them in time:
Disc brake pads replacement
Depending on the pad material, condition of the roads on which you drive and the speed at which you drive, brake pads require replacement after 40,000 to 113,000 kilometres.
Rotors replacement
The brake rotors last from 80,000 to 113,000 kilometres or even more unless they are damaged due to overheating or if the pads are not replaced in time.
Brake Fluid replacement
The brake fluid is the fuel on which the whole brake system runs. You should check it after every 39,000 to 58,000 kilometres. However, in case of a leak, inspect it immediately. If there is a fault with it, you must attend to brake fluid replacement on priority.
Other parts such as pistons and cylinders are meant to last the entire lifetime of the vehicle. However, they might get damaged in a car accident, due to debris or some other reason.
The Cost of Disc Brake Replacement
The cost of disc brake replacement varies based on which part needs replacement, which service provider you opt for and your car type. However, mostly, the recommendation is to replace car brake pads and the product cost starts from AED 40. Meanwhile, the cost for getting it replaced by a professional starts with AED 100+. You can also buy braking pads in the UAE online.
This is all about how disc brakes work. If your car has a disc brake system and it is not functioning properly, you might need to replace a component. If your car continues to malfunction even after brake replacement and other repairs, it is time to get a new one. Check out these used cars for sale in the UAE to find what you are looking for.
Brakes ensure your safety while driving and there is no room to ignore a warning. Therefore, be aware and fix the brake issues in the first instance.
Find out more about the working of vehicles on the UAE’s top auto blog.