Single-unit air brakes practice quiz

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Single-unit air brakesQuestion 21 of 200

Correct19%4 of 21 answered

Incorrect81%17 of 21 answered

How does a spring-brake modulator help the driver stop after primary-system pressure is lost?

AIt exhausts spring-chamber air in proportion to the service application.Your answerCorrect answer

BIt increases drive-axle tire pressure.

CIt bypasses the secondary service brakes.

DIt locks the foot valve in the released position.

Correct.

A normal foot application makes the modulator proportionally exhaust spring-brake air, adding controlled spring force to the remaining front-brake effort. (Guide p. 167)

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