What is the Principle of Air Brakes?
2 Answers
The working principle of air brakes is that when the brake pedal is pressed, the pull rod drives the brake valve arm downward, using the pin shaft as a fulcrum to press the upper end, causing the intake ports of the upper and lower chambers of the brake valve to connect with the outlet ports of the chambers respectively. This allows the air in the front and rear chambers of the storage cylinder to enter the rear and front brake chambers through the upper and lower chambers of the brake valve, thereby activating the brake valve. The system actuator then begins to work. When the brake pedal is released, the brake valve connects to the atmosphere to release the brakes. The differences between hydraulic brakes and air brakes in automobiles are as follows: 1. Different working principles: The working principle of air brakes is as described above. Hydraulic brakes work through hydraulic disc brakes and hydraulic transmission braking. 2. Different characteristics: Air brake features: In addition to the master cylinder, wheel cylinders, and connecting pipelines, air brakes also include an air pump (connected to the engine via a belt), an air storage tank, a high-pressure controller (adjusting pressure, which can reach up to 8 atmospheres), a relay valve, and other components. They require more installation space and have a more complex structure. To ensure safety, rear brake wheel cylinders now use air braking (increasing cost and complexity). Air brakes react quickly, provide harsh braking, and have strong braking force (due to high air pressure, up to 8 atmospheres). Hydraulic brakes have a simpler structure and require less installation space. They only need the master cylinder, wheel cylinders, a fluid reservoir, and connecting pipelines, without requiring additional auxiliary equipment. Hydraulic brakes react slightly slower, provide smoother braking, and have less braking force.
Having driven heavy trucks for several years, I'm quite familiar with the principle of air brakes. The entire system operates using compressed air, with high-pressure gas stored in air tanks. When you press the brake pedal, the control valve opens, allowing air to flow into the brake chamber and push against the diaphragm. The diaphragm expands outward to press the brake shoes against the drum, creating friction to slow down the vehicle. This method is more powerful than hydraulic brakes, especially when carrying heavy loads on slopes where failure is not an issue. I regularly check the air pressure gauge, maintaining it around 100 psi. It's also essential to periodically drain the accumulated water at the bottom of the air tanks to prevent freezing in winter, which could cause malfunctions. After prolonged periods of inactivity, it's important to accelerate slowly when starting up to allow the air system to rebuild pressure, ensuring the brakes remain responsive and safety always comes first.
