The safety valve is designed to protect the air system from overpressurization. It opens automatically at 150 PSI to release excess air pressure. If the safety valve must open, something is wrong with the system, likely a malfunctioning governor.
The CDL (Commercial Driver License) exam tests your knowledge of commercial driving rules, safety procedures, and vehicle operation. You must score 80% or higher to pass the written knowledge test. The exam covers general knowledge, air brakes, combination vehicles, and various endorsements.
This question is from the CDL Air Brakes Test #2 section. Practice with more questions from this category to build confidence before taking the official DMV test.
Browse All Free CDL Practice Tests →