CDL · Air brakes
On an air brake system, what pressure does it normally take for the safety valve to open?
Correct answer: At 150 psi.
Answer options
- AAt 125 psi
- BAt 150 psi Correct
- CAt 200 psi
Why
The safety valve is fitted to the first tank the compressor fills and is normally set to vent at 150 psi, well above the governor's cut-out point of about 125 psi. It lets air escape only if a faulty compressor or governor allows pressure to climb too high.
About this question
Topic: Air brakes License: CDL
Part of these practice sets:
Where it applies: Asked in every state.
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This question is part of How Air Brakes Work (18 questions). Take the full set and check your score.
Practice How Air Brakes WorkMore questions from How Air Brakes Work
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