UniDrive Test

It's not recommended to take park springs apart. Why is this?

There are no repairable parts inside
It's too tough a job
Only the top mechanical team could do this
No reason

The capacity of a service tank is set according to what?

The size and number of brakes installed in the axel group
The year the tractor was manufactured
None of the above
According to OEM specifications

What does air brake antifreeze essentially do?

To keep the air hoses from freezing
Nothing
To prevent the air from freezing
To prevent rubber components in the valves from drying out

Since not all trailers should have alcohol-based antifreeze, how would you know if they should?

You would be able to smell it
There will be a decal fitted to the front of the trailer warning against alcohol use
The year the trailer was built
You would have to trust your maintenance team

How much full-service brake applications should the air tank volume capacity be capable of providing?

a minimum of 6 full-service brake applications for power units and 4 full-service applications for trailers
a minimum of 10 full-service brake applications for power units and 10 full-service applications for trailers
A minimum of 12 full-service brake applications for power units and 8 full-service applications for trailers
A minimum of 8 full-service brake applications for power units and 12 full-service applications for trailers

Which is not part of the service brake circuit?

Control valve
The air dryer gauge
Brake chambers
Air tank protected by a check valve

What does AD-IS refer to?

None of the above
Air Dryer Integrated Solution
Automatic Drying Isolation System
Automatic Documentation Into Solids

Spring park brakes begin to apply if system air pressure drops below what pressure?

60 psi
40 psi
30 psi
50 psi

A long stroke chamber has a total stroke of...

3 inches
3 1/2 inches
2 1/2 inches
2 inches

When the brakes are released, where is the air typically released through?

Through the quick release valve
Through the couplers
Through the rotors
Through the air dryers

What do the air pressure gauges measure?

Air pressure from the primary tank
Air pressure from the secondary tank
The air in the park brakes
Air pressure from both primary and secondary tanks

Power units have two service circuits: one for the steering axel. What is the other one?

The last axel
The power axel
The drive axel
The trailer axel

What do brake chambers do?

Convert air pressure into mechanical force
Hold the air to be used for the brakes
Houses the brakes until they are needed
None of the above

What does Type 20 typically refer to?

The typical size of brake chambers for power axels
Nothing
The typical size of brake chambers for trailer axels
The typical size of brake chambers for steering axels

What is the typical size of brake chambers for load bearing axels?

Type 20
Type 30
Type 15
Type 40

Which statement is false? During a brake application...

Air pressure gauge drops
Air pressure flows through the chambers
Control valve is applied
Air volume in the circuit is lost

How much are the service capable of handling?

350 psi
At least five times the compressor cut-out pressure or 500 psi, whichever is greater
300 psi
250 psi

What is the purpose of the Commercial Vehicle Safety Alliance (CVSA)?

It's club for all commercial vehicle drivers
None of the above
To standardize commercial vehicle inspections so that defects are applied equally throughout North America
To record all deficiencies with commercial vehicles across North America

Are trainer service and park circuits the same as truck and bus circuits?

Yes
Only the same as truck circuits
Only the same as bus circuits
No

The low air alarm is set to activate if air pressure drops below what psi?

50 psi
70 psi
60 psi
80 psi

What allows the brakes to release more rapidly?

When air pressure in the brake chambers exhausts through the quick release valve
When the chambers are not full of air
When the driver releases their foot from the brake pedal
Nothing

How can spring brakes be manually released?

You can't
With a hand control
With a release bolt
With a foot control

When do the tanks drain properly?

After sitting idle for two hours
Not until the air pressure is depleted and the contamination settles down and starts to drip from the tank
None of the above
Once the rpm is at 900 rpm

What is the purpose of a check valve?

It protects the service tanks from air supply failure
It checks that the hoses are running smoothly
None of the above
It checks the service tanks for air

How many air lines go to the trailer?

One
Two
Three
Four

To reduce lag time, what is installed near the brake chambers?

Larger glad hand couplers
Nothing
A relay valve
Larger air lines

When the park control valve is pulled, what happens?

The park brakes are released
None of the above
Air is exhausted and the park spring expands and applies the foundation brake
It prepares the brakes to application

Air pressure for the park circuit is delivered from which tank?

Whichever tank has the least amount of pressure
The secondary tank only
The primary tank only
The higher pressure of either the primary or secondary tank

The park brake control valve pops out when the pressure drops to what psi?

60 psi
30-55 psi
5 psi
20-45 psi

Does every axle group will have an independent service brake circuit?

Some do
No
Just the last axle group
Yes

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