Understanding Brake Systems: The Science Behind Safe Stopping

 Understanding Brake Systems: The Science Behind Safe Stopping


Functions of a Brake System

The primary purpose of a brake system is simple yet critical:

  • Reduce vehicle speed or bring it to a complete stop.

  • Hold the vehicle stationary when parked.

  • Control speed on slopes during downhill driving.

Classification of Brakes

Brakes can be classified in various ways:

  1. By location – Wheel brakes, Transmission brakes

  2. By method of operation – Mechanical, Hydraulic, Air, Electric

  3. By construction – Drum brakes, Disc brakes

  4. By application – Service brakes (foot-operated), Parking brakes (hand-operated)

Drum Brakes

A drum brake consists of brake shoes inside a rotating drum attached to the wheel. When the brake pedal is pressed, the shoes expand outward to press against the drum, creating friction that slows the wheel.

Leading Shoe and Trailing Shoe

  • Leading Shoe: Rotates into the drum surface, creating stronger braking force.

  • Trailing Shoe: Rotates away from the drum surface, providing less braking force.

Self-Energizing Action

In drum brakes, the rotation of the drum helps pull the shoe tighter against the surface, reducing the pedal effort required.


Hydraulic Brakes

Hydraulic brakes use brake fluid to transfer force from the pedal to the brake shoes or pads.

  • Brake Bleeding: A process to remove air bubbles from the hydraulic system to maintain efficiency.


Air Assisted Hydraulic Brakes

These combine compressed air and hydraulic pressure, reducing the driver’s effort in heavy vehicles.

Air Brakes

Used mainly in buses, trucks, and trains, air brakes operate entirely using compressed air.

Layout Components & Functions:

  • Compressor: Generates compressed air.

  • Reservoir: Stores the compressed air.

  • Brake Valve: Controls the air flow to brakes.

  • Brake Chambers: Convert air pressure into mechanical force.

  • Application: Heavy-duty and commercial vehicles.

Disc Brakes

Disc brakes use a flat disc (rotor) attached to the wheel and brake pads that squeeze it to create friction.

Construction and Working:

  • Rotor (Disc): Rotates with the wheel.

  • Caliper: Holds brake pads and piston.

  • Pads: Friction material pressed against the rotor by the caliper piston.

When the pedal is pressed, hydraulic fluid pushes the piston, pressing pads against the rotor for braking.


Disc vs Drum Brakes

Feature

Disc Brakes

Drum Brakes

Cooling

Better heat dissipation

Poorer cooling

Braking Power

More consistent

May fade with heat

Maintenance

Easier pad replacement

More complex shoe replacement

Cost

Generally higher

Lower


Brake Troubles and Their Causes

  • Spongy Pedal: Air in the hydraulic line.

  • Brake Fade: Overheating reduces friction.

  • Pulling to One Side: Uneven brake adjustment or worn pads.

  • Noisy Brakes: Worn-out pads or drums.

Anti-Lock Brake System (ABS)

ABS prevents wheels from locking during sudden braking, maintaining steering control.


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