Brake fluid transfers the force of your foot pressing on the brake pedal to the brakes at all four wheels. Fluid-filled, air-free channels extend from the master cylinder in the engine compartment through brake lines (rigid tubes) and flexible hoses to cylinders that activate calipers or drum brakes. In newer cars, antilock braking system hardware is an intermediate component. Brake fluid reservoirs are often constructed of translucent plastic to simplify checking the fluid level. Some cars incorporate a warning light to indicate if the level drops too low. A healthy brake system won’t lose fluid, though the level may decrease as the brake pads wear. Dramatic fluid loss is cause for investigation.
