What three systems make up modern air brake systems?

The three systems that make up modern air brake systems are the service brakes, parking brakes, and emergency brakes.

The service brake system is the primary braking system used for normal driving. It is designed to slow down or stop the vehicle when the driver applies the brake pedal. This system relies on compressed air to create the necessary braking force and engages the brake shoes or pads, bringing the vehicle to a halt.

The parking brake, also known as the hand brake or emergency brake, is designed to keep the vehicle stationary when parked. It is a crucial safety feature that prevents the vehicle from rolling, especially on inclines. The parking brake can be applied regardless of whether the service brake system is operational, serving as a backup to secure the vehicle.

The emergency brake system is intended for use in situations where the service brakes fail. This system is a separate mechanism that can be activated in emergencies. It helps to safely bring the vehicle to a stop if the primary braking system malfunctions, ensuring the safety of the driver and passengers.

Together, these three systems ensure that air brake-equipped vehicles are safe, reliable, and capable of handling various driving conditions.