Automotive brakes — the service operation that removes trapped air from hydraulic brake lines and cylinders in order to restore a firm pedal and proper braking response is called:

Introduction / Context:
Hydraulic braking systems rely on an incompressible fluid column to transmit pedal force to calipers or wheel cylinders. Air trapped in the system compresses under pressure, causing a spongy pedal and reduced braking effectiveness. The maintenance procedure that purges this air is a standard workshop task and is crucial after component replacement or fluid loss.

Given Data / Assumptions:

• System type: hydraulic brakes with master cylinder and calipers or wheel cylinders.
• Problem: air entrainment or service interruption introducing air bubbles.
• Goal: restore solid pedal feel and correct brake bias.

Concept / Approach:

The process of bleeding uses controlled opening of bleed screws at the calipers or cylinders while pressurizing the system (manual pedal, pressure bleeder, or vacuum bleeder) to expel air bubbles until a solid, bubble-free fluid stream emerges. Sequence matters on multi-circuit systems, and maintaining fluid level prevents reintroducing air at the master cylinder. Proper bleeding restores hydraulic integrity and consistent braking response.

Step-by-Step Solution:

Verification / Alternative check:

Service manuals specify bleeding after component replacement or any low-fluid event. Scan-tool assisted bleeding may be required on systems with ABS modulator valves.

Why Other Options Are Wrong:

Trapping — Opposite of the desired outcome; not a service term.
Tapping — Not a recognized hydraulic brake service operation.
Cleaning — May be performed externally but does not remove air from hydraulic lines.

Common Pitfalls:

Allowing reservoir to run dry during bleeding, introducing more air; ignoring the correct wheel order; using the wrong brake fluid specification.

Final Answer:

bleeding