Wear and Tear on Brake Systems

Because of the force that occurs on the brake system when used to slow or stop a ton of steel at highway speeds, brake components wear down over time. Brake fluid exchange is required to ensure the hydraulic fluid running the system remains full and uncontaminated. Brake pad replacement is necessary as the brake pads wear down over time because they are a softer material by nature than the steel of the rotors. Brake rotor resurfacing or replacement is needed because even though they are made of steel or perhaps an alloy with modern vehicles, they can wear down unevenly and no longer provide an even surface for the brake pads to apply pressure on. If a problem arises with any of these individual parts, the brakes aren't able to work effectively.

What Happens when Brakes Fail

Typically, because there are four sets of brakes, one for each wheel, the redundancy assures the vehicle will still be able to stop if one set of brake pads or a rotor wears out unexpectedly or becomes damaged during regular driving. The concept doesn't mean the vehicle is safe to drive at that point, but at least it won't be left barreling down the road. Suppose the brake fluid reservoir or lines become compromised an unable to assist with stopping power. In that case, the brakes will still work, but without the hydraulics will require the driver to manually apply pressure to the brake pedal, which is how cars worked before power brake systems were introduced. Again, it's not a safe way to operate the vehicle, but it can still come to a stop.