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The braking device of high-speed rail and bullet train is a device used to realize train deceleration or stop running to ensure driving safety. The train braking device is composed of an air supply system and an automatic brake valve installed on the locomotive, brakes and foundation braking devices installed on the locomotive and vehicles respectively, and a brake pipe running through the entire train. Air brake relies on compressed air to push the brake shoe (just understand it as the brake pad) to press against the wheel set or brake disc to achieve the braking purpose. The entire braking system is filled with compressed air. There is no leakage after a pressure test for 15min.