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Iowa CDL Permit Test - Air Brakes

(From the 2019 Iowa CDL driver handbook)
Number of questions: 25
Passing score: 20
Directions: This endorsement is required for driving a vehicle with air brakes. To receive this endorsement, applicants must pass a written test. The test consists of 25 multiple choice questions. Each question has three answer choices. To pass, the applicant must answer at least 20 questions correctly. Test questions come from the Iowa Commercial Driver License Manual. Questions come from the chapter covering: Air Brakes. The Air Brakes endorsement may be used with the Class A, B or C CDL.
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1.
What is removed when an air tank is drained?
Water and oil
Ammonia
Liquid cleaners
2.
Air tank drains should:
Only be used by mechanics.
Only be used when it is wet outside.
Be used to drain the tanks completely.
3.
A low air pressure warning signal:
Is not recommended on vehicles with air brakes.
Is required on vehicles with air brakes.
Is optional on vehicles with air brakes.
4.
On flat surfaces, wheel chocks:
Can be used to prevent a parked vehicle from moving.
Make it easier for a parked vehicle to roll.
Should only be used on the front driver's side tire.
5.
Why do large vehicles use air brakes?
Other brake systems squeak too loudly.
Air brakes are very effective systems.
Other braking systems are hard to come by.
6.
What does the air compressor governor do?
It stops the compressor from pumping air.
It turns on the air compressor.
It stores the compressed air.
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