Hydraulic brake system — role of the master cylinder In a typical passenger-car hydraulic braking system, what is the primary function of the master cylinder?

Introduction / Context:
The master cylinder is the heart of a hydraulic brake system. Knowing its function helps in diagnosing issues such as a sinking pedal, internal leaks, or air in lines.

Given Data / Assumptions:

• Conventional systems may include a vacuum booster (servo), proportioning valves, and ABS modulator.
• The master cylinder contains a reservoir and primary/secondary pistons with seals and ports.

Concept / Approach:
When the driver presses the pedal, mechanical force is transmitted (often through a booster) to the master-cylinder pistons. These pistons displace brake fluid and generate hydraulic line pressure that actuates calipers or wheel cylinders using Pascal’s principle.

Step-by-Step Solution:
Pedal force → pushrod → master piston(s).Piston motion closes compensation ports → pressure builds in circuits.Pressure transmitted via lines/hoses to calipers/wheel cylinders → brake force at discs/drums.

Verification / Alternative check:
Pressure gauges placed at outlets rise proportionally with pedal force; leaks or bypassing seals show reduced or unstable pressure, confirming the master’s purpose.

Why Other Options Are Wrong:
Free play adjustment is a mechanical linkage task, not the master’s core function.

Boosting is the vacuum/ hydraulic booster’s role, not the master cylinder's.

Equalization is handled by proportioning/ABS logic; equal pressure is not always desired.

The reservoir stores fluid, but the master’s key role is pressure generation.

Common Pitfalls:
Air in the master or lines prevents pressure buildup; wrong pushrod length can block ports causing drag.

Final Answer:
convert the driver’s pedal force into hydraulic pressure