Which brake system of a motor vehicle functions without any appreciable wear?

The engine brake and the retarder both slow down the vehicle without using friction materials like brake pads or shoes. Instead, they use the engine's internal mechanisms or hydraulic/electric systems to reduce speed, so they do not wear out over time. On the other hand, the compressed air-braking system relies on brake pads pressing against discs or drums, which causes wear and requires regular maintenance. Understanding this helps you recognize that non-friction brakes preserve brake components and extend the vehicle's overall brake system life.