Car Brake Parts And Their Function

The braking system in your car is an arrangement of several components. These include; the master cylinder, brake lines, rotor, brake drum or brake disc, etc. The purpose of these components is to convert your car’s kinetic energy (Kinetic energy is a form of energy that an object has because of its motion) into thermal energy (heat) by generating friction between the moving surfaces - rotor/brake drum, and stationary surface - brake pads/shoes, thus stopping or slowing your car. When you press the brake pedal, the brake pads or the brake shoes rub against the disc or drum. This generates friction and slows or stops the rotation of the wheels, hence bringing your car to a halt.

There are two types of hydraulic brakes based on frictional contact:

1. Drum brakes (internal expanding) 

It is a form of brake system in which the brake shoes are housed in a drum that is mounted to the wheel hub.  When the outer section of the drum spins with the wheel, while the inner half remains stationary. When the brakes are applied, the actuating system (wheel cylinder) forces the brake shoes to expand, causing the outer frictional surface of the brake shoes to make frictional contact with the revolving drum component. This results in the vehicle stopping or decelerating.

2. Disc brakes (external contracting)

In this braking system, a disc rotor is coupled to the hub of the wheel in such a way that it spins with the wheel. This disc rotor is clamped in between the caliper which is connected to the vehicle's knuckle or upright. The caliper houses the brake pads along with the actuation system (caliper cylinder/ piston). When the brakes are applied, the actuation system contracts the attached brake pads, causing frictional contact with the revolving disc rotor and resulting in vehicle braking.

There are two types of hydraulic brakes on the basis of brake force distribution:

1. Single-acting hydraulic brakes

In this type of hydraulic brake, a single cylinder type of master cylinder is used. This cylinder produces restricted hydraulic pressure that can only be delivered in one direction.

2. Dual-acting hydraulic brakes

In double-acting hydraulic brakes, a twin or tandem master cylinder is used which provides higher brake force. This force that is generated can be transferred in both rear and front directions.

Various components, set in an arrangement work together and form the braking system. These components are able to cause the braking effect in a vehicle. Following are the braking parts found in a hydraulic braking system.

• Brake Booster

• Master Cylinder

• Brake Fluid

• Brake Fluid Reservoir

• Brake Lines

• Disc Brake

• Drum Brake

• Parking Brake / Hand Brake

• ABS (Anti-Lock Braking System)

  
  

Constant Viscosity: The brake fluid requires a constant viscosity across wide temperature ranges (viscosity is the measure of resistance in the flow of a fluid).

High Boiling Point: The boiling point of the braking fluid must be high. Since friction from the brake pads generates a lot of heat. If the fluid around the brakes reaches its boiling point, it will evaporate, making the brakes ineffective.

Special Additives: Brake fluid requires special additives that prevent corrosion in the brake lines. The best way to determine the right brake fluid type for your car is to check the owner’s manual.

Brake line: These are rigid Steel lines that connect the master cylinder and the hoses. They cannot withstand suspension travel and side-to-side movement during turning.  Therefore flexible hoses are used for this purpose namely steel stainless steel, steel, soft steel, and nickel-copper alloy. Galvanized mild steel is the most commonly used material for brake lines.

Brake Hoses:  Brake hoses are flexible tubes that carry brake fluid from a brake line fixed to the car's body to the brake caliper or wheel cylinder. They are also known as soft brake lines. Based on material, they are of two types of brake hoses:

• Rubber hoses: Since rubber is flexible, durable, and has a long life, it is perfect for brake hoses. Though many car makers provide rubber hoses as they cost less and give satisfactory performance, rubber hoses tend to expand under high brake fluid pressure. 

• Braided stainless steel hoses: In this, the inner tube is wrapped in a stainless steel mesh. Stainless steel hose is much stronger than rubber. It is more expensive and is commonly used in high-performance applications.

Disc brakes, which were initially intended for the aviation industry, are widely used due to their fade resistance, despite their greater cost. Although some four-wheel systems exist, discs are typically put on the front wheels and standard drum units are kept at the back. There are three primary parts to a disc brake;  brake rotor, brake pad, and brake caliper.

A brake drum is attached to the wheels and contains the brake shoes with brake linings (friction material) that press against the drums from the inside to provide braking force. When the brake pedal is pressed, the brake shoes are pushed outwards against the inner surface of the brake drum This generates friction which slows the spinning of the wheels. A brake drum is typically made of cast iron.

Brake shoe is a curved metal piece with a friction substance attached to one side. When you apply brakes, a wheel cylinder in the drum brake system presses the brake shoe outward, against the inside of the drum. As a result of the friction between the lining and the drum, your car slows or stops.

When the brake shoes are seated to the drum, the self-adjusting mechanism performs a crucial part in ensuring optimum brake balance. In order for the drum brakes to function correctly, the brake shoes must remain close to the drum without touching it. When they travel too far away from the drum, the piston will require more fluid to traverse the distance, and when you press the brakes, your brake pedal will sink closer to the floor. As a result, most drum brakes include self-adjusting systems.

With this information on brake system parts and their functionality, you will be more in sync with the working of your vehicle. This article is a great reference for the future, we recommend bookmarking it and review when in need. Browse relevant products, and read the FAQs for more information. Be smart, and be safe!