Brake Systems & ABS
Disc and drum brake components, master cylinder, brake fluid types, bleeding procedures, ABS operation, brake diagnostics, and parking brake systems.
- Explain hydraulic brake system operation and Pascal's Law
- Identify disc brake and drum brake components and their functions
- Select the correct brake fluid type and describe bleeding procedures
- Describe ABS and stability control system operation and diagnosis
- Diagnose common brake complaints including pull, pulsation, and noise
Lección 1
Hydraulic Brake Fundamentals & Master Cylinder
How Hydraulic Brakes Work
Every modern vehicle uses a hydraulic braking system that relies on Pascal's Law - pressure applied to a confined fluid is transmitted equally in all directions. When you press the brake pedal, the master cylinder converts mechanical force into hydraulic pressure, which travels through brake lines to each wheel's brake caliper or wheel cylinder.
The Master Cylinder
The master cylinder is the heart of the hydraulic brake system. Modern vehicles use a tandem (dual) master cylinder that has two separate pistons and two separate hydraulic circuits. This design means that if one circuit fails (such as from a brake line leak), the other circuit still provides braking on two wheels.
The brake fluid reservoir sits on top of the master cylinder and feeds fluid to both circuits. Inside, the primary piston and secondary piston create independent pressure in the front and rear circuits.
Exam Fact
A spongy brake pedal indicates air in the hydraulic system. Air is compressible while brake fluid is not - air pockets absorb pedal pressure instead of transmitting it to the brakes.
Brake Booster
The brake booster (also called a vacuum booster or power brake booster) is mounted between the brake pedal and the master cylinder. It uses engine vacuum to multiply the driver's pedal force, reducing the effort needed to stop the vehicle. A failed brake booster causes a hard brake pedal that requires much more foot pressure to stop.
Brake Warning Light
The brake warning light on the dashboard illuminates when the parking brake is engaged, when brake fluid level is low, or when there is a pressure difference between the two hydraulic circuits. A low fluid level often indicates worn brake pads (fluid displaces into the caliper as pads wear) or a leak in the system.
The master cylinder converts pedal force into hydraulic pressure using Pascal's Law. A spongy pedal means air in the system, while a hard pedal suggests a failed brake booster.