Brake Systems Flashcards

What is the purpose of the brake master cylinder?

Answer: To convert mechanical force from the brake pedal into hydraulic pressure distributed to the wheel brakes

The master cylinder is a hydraulic pump that converts the mechanical force applied by the driver through the brake pedal into hydraulic pressure, which is transmitted through brake lines to actuate the wheel brakes.

What does the brake pedal feel like when there is air in the hydraulic brake system?

Answer: Soft and spongy

Air in the hydraulic system is compressible, unlike brake fluid. When the pedal is applied, the air compresses before the fluid can build full pressure, resulting in a soft, spongy pedal feel.

What is the purpose of the proportioning valve in a brake system?

Answer: To reduce hydraulic pressure to the rear brakes to prevent premature rear wheel lockup during braking

During braking, weight transfers to the front wheels, reducing rear wheel traction. The proportioning valve limits pressure to the rear brakes, preventing them from locking up before the front brakes.

What causes brake fade during repeated hard braking?

Answer: Excessive heat reducing the friction coefficient of brake pads and potentially boiling brake fluid

Repeated hard braking generates extreme heat. The brake pad friction material loses effectiveness at high temperatures, and if fluid boils, gas bubbles form in the lines creating a compressible condition, both reducing braking effectiveness.

What is the minimum acceptable brake pad thickness for most vehicles according to Canadian standards?

Answer: 2 mm (excluding backing plate)

Most Canadian jurisdictions and manufacturer standards require brake pad replacement when friction material reaches 2 mm thickness (not including the metal backing plate). Some manufacturers specify 3 mm as the service limit.

What does a pulsating brake pedal during normal braking typically indicate?

Answer: Brake rotor lateral runout (thickness variation or warping)

A pulsating pedal during braking is caused by brake rotor lateral runout or thickness variation. As the rotor rotates, the thick and thin spots alternately push the caliper piston in and out, creating a pulsation felt through the pedal.