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54 Cards in this Set
- Front
- Back
Under normal conditions in order to engage the parking brakes driver: |
Let the air out of air brake system |
|
Air braking takes more time than hydraulic braking because air: |
Takes more time to flow through the lines than hydraulic fluid |
|
The applicator pressure gauge shows how much air pressure you: |
Are applying to the brakes |
|
The spring brakes used on the chambers in a straight truck will bring you to a stop when air pressure drops below ____psi |
20 |
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Some air brake systems have an alcohol evaporator. What may happen if you don't keep the proper level of an alcohol? |
Ice may form in the air storage tank and cause a brake failure |
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Your truck or bus has a dual air brake system. If a low air pressure warning comes on for only one system, what should you do? |
Bring your vehicle to a complete stop right away and safely park. Continue only after the system is fixed |
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Why drain water from compressed air tanks? |
Water can freeze in cold weather and cause brake failure |
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The safety valve is set automatically when pressure is: |
150 |
|
Your truck has a dual air system and one of the systems loses its pressure. What will happen? |
Either the front or back brake will not be fully operational |
|
Parking or emergency brakes of trucks and buses can be legally held on by_____pressure |
Spring |
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If your truck or bus has dual parking control valves, you can use pressure from a separate tank to: |
Release the spring emergency/Parking brakes to move a short distance |
|
If your truck has a properly functioning dual air brake system and minimum size air tanks the air pressure should build up from 85 to 100psi within how many seconds? |
45 |
|
How should you check that your service brakes are working properly? |
Park on level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at 5mph. Then apply brakes firmly |
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A straight truck or bus air brake system should not leak at the rate of more than_____psi per minute with the engine off and the brakes released |
2 |
|
During normal driving, spring brakes are usually held back by |
Air pressure |
|
The air compressor stops pumping air at what psi? |
125 |
|
The driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks falls below______psi |
60 |
|
Excessive use of the service brakes results in overheating which can lead to: |
Expansion of the brake drums |
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The most common type of foundation brake found on heavy vehicles is the: |
S cam drum |
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If you must make an emergency stop,you should brake so you: |
Can steer and so your vehicle stays in a straight line |
|
If your vehicle has an alcohol evaporator, every day during cold weather you should: |
Check and fill the alcohol level |
|
The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than: |
3 psi in one minute |
|
The braking power of the spring brakes: |
Depends on the service brakes being in adjustment |
|
The air brake lag distance at 55mph on dry pavement adds about____ft |
32 |
|
Total stopping distance for air brakes is longer than that for hydraulic brakes due to_____distance |
Brake lag |
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It is accepted that too much heat caused by using ur brakes too often can also cause: |
Brake to fade or fail |
|
Repeatedly partially releasing and pressing the brake pedal may result in: |
A loss of brake air pressure |
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The brake system that applies and releases the brakes when the driver uses the brake pedal is the___Brake system |
Service |
|
A slack adjusters free play needs to be adjusted if it is more than about___how many inches when you pull hard on it? |
1 inch |
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An air brake system is fully charged at what psi? |
125 |
|
The brake pedal in an air brake system: |
Control the air pressure applied to put on the brakes |
|
The s cam: |
Forces the brake shoes against the inside of the brake drum |
|
All air brake equipped vehicles have |
A supply pressure gauge |
|
With air brake vehicles, the parking brakes should be used: |
Whenever you leave the vehicle unattended |
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Which of these is not a proper time to apply the parking brakes? |
To brake vehicle very hard, in other word when coming down the steep grade |
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If the spring brakes are on, when should you push the brake pedal? |
Never |
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To check the free play of manual slack adjusters of s cam brakes, you should park on: |
Level ground, chock the wheels and release the parking brakes |
|
The use of brakes on a long and steep downgrade under normal conditions is only a supplement to: |
The braking effect of the engine |
|
The most important thing to do when a low air pressure warning comes on is: |
Stop and safely park as soon as possible |
|
The parking or emergency brake on a heavy vehicle can only be held in position by something that Cannot leak away, like: |
Spring pressure |
|
When brakes are applied the brake shoe will press against the: |
Brake drum or disc |
|
The safety valve discharges automatically at the pressure of: |
150 |
|
Emergency stab braking is: |
Press on the brake pedal as hard as you can, release the brakes when the wheels locked, put on the brakes again when the wheels start rolling |
|
If air pressure is not built up within the correct amount of time, then: |
Your air pressure may drop to a low point while driving, requiring an emergency stop |
|
The safety valve reduces pressure at___psi |
150 |
|
The supply pressure gauge shows how much pressure: |
Is in the air tanks |
|
Your brakes are fading when: |
You have to push harder on a brake pedal to control your speed on a downgrade |
|
The air compressor governor controls: |
When air is pumped into the air tanks |
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Modern air brake system combine three different systems. They are the service, the parking, and the_____ |
Emergency brakes |
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The proper use of the brakes when going down a long steep grade after selecting a proper gear is to brake until your speed is about___mph below the posted speed for your safety and release your brake. |
5 |
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In ideal conditions a truck or bus with an air brake going at 55 mph would require stopping distance of how many feet? |
More than 300ft |
|
The stop light switch: |
Turns on your brake lights to warn drivers behind you |
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It is not safe to drive a vehicle that has brake drums with cracks that are longer than___of the width if the friction area. |
1/2 |
|
To test air service brakes you should: |
Brake firmly while slowly moving forward |