Most cars today have hydraulic brakes. That means that when you press the brake pedal, fluid is sent from the master cylinder to the calipers or wheel cylinders. The fluid then applies pressure to the pistons in the calipers or cylinders, which push the brake pads or shoes against the rotor or drum. This creates friction, which slows down your car.
The master cylinder is a reservoir that holds brake fluid. When you press on the brake pedal, a plunger in the master cylinder pushes fluid through a series of tubes and hoses to the calipers or wheel cylinders. The pressure of this fluid activates a piston in each caliper or cylinder, which presses one side of the brake pad or shoe against either the rotor (in a disc brake) or drum (in a drum brake). As more pressure is applied to the brakes, more fluid flows and more braking force is generated.
Brake fluids are designed to withstand high temperatures and pressures without boiling; they also prevent corrosion in your braking system components. Over time, however, moisture can enter your system and cause problems such as premature wear, rusting and even failure of some parts. That’s why it’s important to have your brakes checked regularly and to flush out your system every few years