The fluid which provides pressure to the wheel brakes is supplied by which combination?

• A. The master cylinders and the power package
• B. The master cylinders and the brake reservoir
• C. Cylinders at the tops of the brake pedals
• D. The master cylinders and the brake units

Answer: (B)

The pressure for the wheel brakes comes from a hydraulic system where the master cylinders generate the pressure and the brake reservoir provides the fluid to keep the system topped up. When you press the brake pedal, the master cylinders push brake fluid through the brake lines, creating hydraulic pressure that moves the calipers or wheel cylinders to squeeze the brake pads against the rotors. The brake reservoir feeds fluid into the master cylinders to replace what’s used and to compensate for fluid expansion, ensuring there’s always enough fluid and no air enters the system.

That’s why the combination of the master cylinders and the brake reservoir is the correct source for the pressure-generating fluid. The other options don’t fit because power packages aren’t the standard source of hydraulic pressure, there aren’t cylinders at the tops of the brake pedals to generate the pressure, and the brake units themselves don’t supply the fluid—they receive the pressurized fluid from the master cylinders.