What Is a Disc Brake: Types and Working Mechanism

Disc brakes are a part of a hydraulic brake system that helps slow down or stop a vehicle. They use callipers to squeeze the brake pads against a flat disc attached to the wheel to generate friction. This slows down the rotating speed of the shaft.

The name disc brake comes from the disc shape of the rotor attached to the wheel. Disc brakes are widely used in automobiles, aircraft, heavy machinery, etc. due to their effectiveness and heat dissipation.

The disc brake system involves several components. They work in sync to slow down or stop vehicles. The main parts of a disc brake include the following:

Disc (rotor): It is the largest component in the disc brake system. It is attached to the wheel hub and spins with it. Rotors are usually made of steel or cast iron.

However, few high-end cars have carbon ceramic rotors. Braking generates a lot of friction and heat. Therefore, most vehicles have ventilated discs for better heat dissipation

Brake pads: They press against the disc to create friction. Brake pads have a metal part called a shoe to which a lining is attached. It is the lining that comes in contact with the rotor. It can be made of ceramic, organic or semi-metallic materials

Piston: It is the cylinder attached to the brake system’s hydraulics. It is responsible for moving the brake pads against the rotor when brake pedals are pressed

Calliper: It is fitted over the rotor. The calliper holds the piston and the brake pads. It also consists of ducting for brake fluid. Its main function is to press the brake pads into the rotor

Sensors: A few modern cars have brake pads with sensors to inform if the pads are worn out

Now that you are familiar with the disc brake components, let us understand how they work together to help you stop or slow down a vehicle:

• When you press the brake pedal, the hydraulic fluid is pushed into the brake lines.

• This helps the brake pads to squeeze against the rotor.

• The harder you press the brake pedal, the more pressure is created in the brake lines.

• The increased pressure allows the pistons in the calliper to push harder against the brake pads.

• The pads grip the disc from both sides to generate friction and slow down or stop the wheel.

• When you release the brake pedal, the pistons retract.

• This helps the brake pads to move away from the disc allowing your vehicle to move.

Following are the types of disc brakes:

Cross-drilled disc brake

It is the most common disc brake system in India. It consists of cross-drilled holes on the disc that help dissipate the heat and gas generated while braking.

However, cross-drilled discs are prone to cracking. Due to this, they are preferred in high-performance sports cars where weight reduction is necessary.

Cross-slotted disc brake

This system has slots or channels cut onto the disc. The slots can be of varying width and cut at different angles. They help disperse the heat generated during braking and enhance the braking performance. Cross slotted disc brake system also prevents brake fade leading to consistent performance in the long run.

Wave disc brake

It is also referred to as the petal disc brake system. In this system, the outer boundary of the disc is cut into waves. This provides an extra surface for the brake pads for gripping the disc while rotating.

The curved boundary also ensures better heat dissipation. The wave disc brake system is also lightweight. This provides higher acceleration capacity.

Disc brakes are widely used in the following:

• Automobiles

• Bicycles

• Aircraft

• Industrial machinery

• Racing vehicles

Here’s a list of advantages of a disc brake system:

• Enhanced braking performance

• Better heat dissipation

• Easy and quick replacement of pads

• Lightweight

• Less prone to brake fade

• Customisable

• More predictable response especially during wet conditions and high temperatures

While car disk brakes are favoured against their drum brake counterparts, they have the following limitations:

• Installation is more expensive than drum brakes

• Less effective in muddy and wet conditions

• Brake pads require frequent replacement due to early wear

• It may generate noise while braking

So, now you know what critical role those discs on your car’s wheels play in road safety. The disc braking system has a few drawbacks. However, it is still considered superior to the drum brake system.

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What materials are used for disc brakes?

Disc brakes are usually made of cast iron and carbon. Carbon is used due to its high thermal resistance and lightweight.

Do all vehicles have disc brakes?

Most vehicles today have disc brakes on all four wheels or disc brakes on the front wheel and drum brakes on the rear.

Who invented disc brakes?

Disc brakes were invented by British engineer Fredrick W. Lanchester in 1902.

Which is better, disc or drum brakes?

Disc brakes are more powerful than drum brakes when it comes to braking. They work efficiently in all weather conditions.