In the pneumatic braking system of a bus, what main job does the unloader valve perform?

Question

DentroTest · Accepted Answer

The unloader valve (or pressure regulator) in a purely pneumatic braking installation has the fundamental job of protecting the integrity of the system against overpressure. When the compressor supplies air and the air tanks reach the maximum service pressure set by the manufacturer (calibrated pressure), this valve opens and releases the excess air to the outside to avoid damage to pipes, tanks and other pneumatic components. Channeling air to the semi-trailer is a function of the coupling heads and the trailer control valves, and eliminating bubbles in hydraulic fluid lines wrongly mixes components of a hydraulic system with those of a pneumatic one.

In the pneumatic braking system of a bus, what main job does the unloader valve perform?

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