Hawaii CDL — Air Brakes: Safe Driving Practices Practice Test

Question 1

The final air brake check takes two leakage readings on a single vehicle: one with the brakes released and one with the foot brake held down. How do the limits compare?

Accepted Answer

The applied reading allows up to 3 psi a minute, against less than 2 psi with the brakes released — With the brakes released, a single vehicle should lose less than 2 psi in a minute. With the foot brake fully applied, the loss is too much only when it passes 3 psi in a minute. For combinations the figures are 3 and 4 psi.

Answer

Both readings share one limit of 2 psi a minute

Answer

The released reading allows more loss than the applied one

Answer

Neither reading has a limit; you only listen for leaks

Question 2

The ABS requirement reached one kind of air-braked vehicle a year before the rest. Which kind?

Accepted Answer

Truck tractors — March 1, 1997 was the cutoff date for air-braked truck tractors. Trucks, buses, trailers and converter dollies with air brakes came under the rule a year later, on March 1, 1998.

Answer

Buses

Answer

Trailers

Answer

Converter dollies

Question 3

One half of a dual air brake system typically handles the service brakes at the front axle. What else may that same half operate?

Accepted Answer

Possibly the brakes on one rear axle — The system that works the front-axle brakes may also work the brakes on one rear axle. Both halves of the dual system send air to a trailer if there is one.

Answer

The air compressor governor

Answer

Only the trailer's spring brakes

Answer

The stop light switch and nothing more

Question 4

Why does the manual tell you to check brake adjustment often?

Accepted Answer

Brakes can go out of adjustment fast, and heat makes it more likely — Brakes can lose their adjustment quickly, especially while hot. A brake that is out of adjustment stops doing its share, which overloads the others.

Answer

Adjustment changes every time the tanks are drained

Answer

ABS resets the adjustment at each start-up

Answer

Cold weather is the only thing that affects it

Question 5

Each brake release lets a little compressed air escape, so tank pressure drops. What brings the pressure back up?

Accepted Answer

The air compressor — Air lost when the brakes release has to be replaced by the compressor. That is why needless pedal use can empty the tanks faster than the compressor refills them.

Answer

The safety relief valve

Answer

The alcohol evaporator

Answer

The spring brakes

Question 6

Your truck's air tanks have automatic drains. What does the manual say about draining those tanks by hand?

Accepted Answer

A tank with an automatic drain can also come fitted for hand draining — Automatic drains push water and oil out on their own, but the manual adds that such a tank can be set up with a manual drain too.

Answer

It is never possible on a tank with an automatic drain

Answer

It ruins the automatic valve

Answer

It is required every hour in cold weather

Question 7

You climb into an unfamiliar air-braked truck and cannot find an application pressure gauge. What does the manual say about that?

Accepted Answer

That gauge is not fitted to every vehicle — An application pressure gauge shows how much air you are putting to the brakes, but the manual notes that not every vehicle has one. A supply pressure gauge, by contrast, is on every air-braked vehicle.

Answer

The truck may not be driven without one

Answer

It means the truck has hydraulic brakes

Answer

The gauge stays hidden until pressure drops under 55 psi

Question 8

On a tractor, truck or bus with ABS, where is the yellow ABS malfunction lamp?

Accepted Answer

On the instrument panel — Tractors, trucks and buses have their yellow ABS warning lamp on the dash, in the instrument panel. A trailer's lamp is on its left side, at the front or rear corner.

Answer

On the left rear corner of the body

Answer

Under the hood beside the compressor

Answer

On the parking brake knob

Question 9

During the final air brake check, the governor does not cut the compressor in and out the way it should. Why does the manual treat that as a safety problem?

Accepted Answer

The truck may not hold enough air pressure to be driven safely — A governor that is not working properly may fail to maintain the air pressure safe driving needs, so it may have to be repaired.

Answer

The ABS lamp will stay lit

Answer

The spring brakes will never apply

Answer

The brake drums will crack from overpressure

Question 10

In a drum brake setup, what are the vehicle's wheels bolted to?

Accepted Answer

The brake drums — Brake drums sit at each end of the axles, and the wheels bolt onto them. The shoes and linings do their work inside the drum.

Answer

The slack adjusters

Answer

The brake chambers

Answer

The brake shoes

Question 11

The manual gives one air pressure buildup standard for dual air systems and another for pre-1975 single systems. Which one is the dual-system standard?

Accepted Answer

Engine at operating rpm; pressure climbs from 85 to 100 psi in 45 seconds or less — Dual systems are expected to go from 85 to 100 psi in no more than 45 seconds with the engine at operating rpm. The idle-speed, 50 to 90 psi, three-minute figure is the typical requirement for older single systems.

Answer

Engine idling at 600 to 900 rpm; pressure climbs from 50 to 90 psi in 3 minutes or less

Answer

Engine off; pressure climbs from 100 to 125 psi in 1 minute or less

Answer

Engine at fast idle; pressure climbs from 0 to 55 psi in 10 seconds or less

Question 12

A driver says that because every vehicle built since 1994 has automatic slack adjusters, there is nothing to check on a newer truck. What does the manual say?

Accepted Answer

Automatic adjusters still have to be checked, even though they adjust themselves — Automatic slack adjusters take up slack on their own when the brakes are fully applied, but the manual says they must be checked all the same.

Answer

He is right; automatic adjusters need no checking

Answer

They need checking only on trailers

Answer

They should be tightened by hand before every trip instead

Hawaii CDL — Air Brakes: Safe Driving Practices practice test

Study questions with answers

1. The final air brake check takes two leakage readings on a single vehicle: one with the brakes released and one with the foot brake held down. How do the limits compare?

2. The ABS requirement reached one kind of air-braked vehicle a year before the rest. Which kind?

3. One half of a dual air brake system typically handles the service brakes at the front axle. What else may that same half operate?

4. Why does the manual tell you to check brake adjustment often?

5. Each brake release lets a little compressed air escape, so tank pressure drops. What brings the pressure back up?

6. Your truck's air tanks have automatic drains. What does the manual say about draining those tanks by hand?

7. You climb into an unfamiliar air-braked truck and cannot find an application pressure gauge. What does the manual say about that?

8. On a tractor, truck or bus with ABS, where is the yellow ABS malfunction lamp?

9. During the final air brake check, the governor does not cut the compressor in and out the way it should. Why does the manual treat that as a safety problem?

10. In a drum brake setup, what are the vehicle's wheels bolted to?

11. The manual gives one air pressure buildup standard for dual air systems and another for pre-1975 single systems. Which one is the dual-system standard?

12. A driver says that because every vehicle built since 1994 has automatic slack adjusters, there is nothing to check on a newer truck. What does the manual say?

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