Should the Air Brake Not Be Continuously Pressed?
3 Answers
Air brakes should not be continuously pressed because doing so will deplete the air in the air tank, leading to a loss of braking capability. It also increases the workload of the engine, causing engine vibration. Reasons why air brakes should not be continuously pressed: The principle of air brakes involves using compressed air from the storage tank to inflate the brake chamber, which pushes the brake shoes to achieve braking. Continuously pressing the brake pedal will reduce the air pressure in the tank, eventually leading to insufficient pressure and an inability to brake properly. Additionally, truck brakes are crucial for safety, which is why most truck drivers ensure the air pressure in the air brake system reaches 5-6 Bar before setting off. Consequences of continuously pressing the air brake: Air brakes use a cylinder regulator valve to create resistance against the engine's operation, thereby reducing engine speed and slowing the vehicle. Keeping the exhaust brake engaged for prolonged periods increases the engine's workload, resulting in engine vibration. In severe cases, it can cause the cylinder regulator valve to be forced open and damaged. How the spring brake (parking brake) works: The air pump, driven by the engine, compresses air into high-pressure gas stored in the air tank. One air tank is connected to the brake master cylinder via pipelines. When the driver presses the brake pedal, the upper air circuit opens first, and high-pressure gas from the air tank is transmitted to the relay valve.
Having driven heavy trucks for over 20 years, I know you should never keep the air brake pedal depressed continuously. Air brake systems rely entirely on air pressure to activate the brake pads. If you hold the pedal down, air keeps releasing, causing tank pressure to drop rapidly like a deflating balloon. This can lead to loss of braking power on descents, significantly increasing accident risks. The proper technique is to apply short, controlled taps to manage speed, then release to let the air tanks recharge. Prolonged braking also accelerates component wear - valve diaphragms degrade, leaks develop, and repairs become costly and time-consuming. I constantly monitor my air gauge to maintain safe pressure ranges; developing this habit can be lifesaving. On slopes, use intermittent braking or downshift to assist deceleration rather than relying on continuous pedal pressure. Safety always comes first when driving.
As a regular driver who has long been concerned about driving safety, I must emphasize that continuously holding the air brake is very dangerous. The air pressure system is designed to intermittently recover air, and keeping it pressed can cause air leakage. When the air pressure is too low, the brakes may suddenly fail. Imagine how terrifying it would be to fail an emergency stop on the highway. The correct method is to lightly press for a few seconds and then release, listening for the sound of air pressure recovery to judge. Make it a habit to regularly check the air pump. If the air gauge shows a rapid drop, stop immediately for maintenance. Don't underestimate this; incorrect operations have caused rear-end collisions before. Safe driving relies on details, and timely reactions can avoid trouble.
