What device is used to remove air from a hydraulic brake system?

• A. Master Cylinder
• B. Bleed Valve
• C. Pump
• D. Bleeder Screws

Answer: (D)

Air in a hydraulic brake system makes the pedal feel soft because air compresses. To restore proper braking, you purge that air by bleeding the brakes. The device used at each wheel to vent air and old fluid is the bleeder screw, a small valve on the caliper or wheel cylinder. When you loosen this screw, fluid and any trapped air flow out, while the master cylinder pushes more fluid through the line. You keep the Master reservoir topped up so new fluid can fill the vacuum and air pockets exit, and you repeat at each wheel, typically starting farthest from the master cylinder.

Bleeder screws are specifically built for this venting process. The master cylinder is what creates hydraulic pressure, a pump just moves fluid and isn’t the venting point, and while a bleed valve can refer to a vent in some systems, the wheel-mounted device you open to remove air is the bleeder screw.