Parking or emergency brakes of trucks and buses can be legally held on by ____ pressure.
Answer: C
Spring
Since air pressure will eventually leak away with time, emergency brakes must be activated and held by mechanical force. All commercial trucks require emergency brakes. Currently, those are spring-loaded mechanical brakes.
All choices
- AAir
- BFluid
- CSpring
Why the other answers are wrong
A. Air
Choice A is wrong because air pressure cannot hold parking brakes indefinitely due to leaks.
B. Fluid
Choice B is wrong because fluid pressure is not used to hold parking or emergency brakes on trucks and buses.
CDL Air Brakes Test Info
Questions on Exam
25
Passing Score
80%
Time Limit
Typically 30 minutes; varies by testing location
The Air Brakes test content is federally standardized, so this question applies in every state. Age limits, fees, and testing procedures do vary — check your state's CDL requirements.
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More CDL Air Brakes Practice Questions
- Repeatedly partially increasing and pressing the brake pedal may result in:
- The air compressor governor controls:
- To check the free play of manual slack adjusters of S-cam brakes, you should park on:
- A slack adjuster free play needs to be adjusted if it is more than about ____ when you pull hard on it.
- Stab braking: