Working principle of air brake for large trucks

The hand brake system of this kind of car is usually in a constant braking state with strong springs. When the vehicle is going to run, the driver releases the brake is an inflatable action, and it must reach a certain air pressure to push away the spring, that is, release the hand brake before running. Conventional braking is to lock the transmission shaft with a hand brake, and when the foot brakes, compressed air enters the brake chamber to lock the wheels.

When the driver operates the manual brake valve, the core tube abuts against the control cam under the action of the spring. At this time, the intake valve is closed, the exhaust valve is opened, the exhaust port exhausts to the atmosphere through the core tube and the exhaust port, and the energy storage brake chamber in the compound brake chamber also exhausts to the atmosphere through the quick release valve. So the car is in the parking brake state.

The maximum stroke of the parking brake air chamber push rod is usually greater than that of the service brake push rod by 10%. Therefore, when the service brake push rod has moved to the maximum stroke, but the braking gap is too large, the parking brake air chamber can be deflated, and the service brake push rod can be further pushed out by the energy storage spring to realize complete braking.

Extended data:

Air brake: Air brake can be used as parking brake and emergency brake.

Air brake: Air brake parking brake can only be used when the car is stationary, because its braking torque acts on the transmission shaft. If it is used when the car is running, it is easy to cause serious overload of the transmission shaft and the rear axle, and the left and right wheels may turn in the opposite direction because of the locking of the differential housing, which may lead to deviation or even U-turn when the car is braking.

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