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113 Cards in this Set
- Front
- Back
Which of the following is okay to find I the air brake system? |
Air |
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Air loss in a single vehicle (not a combination unit) should no be more than _______ with the engine off and the brakes on. |
3 psi in one minute |
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The vehicle must have a warning device which comes on when the air pressure in the service air tanks falls below: |
60 psi |
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If the air system should develop a leak, what will keep air in the tanks? |
The one-way check valve |
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Which brake system applies and releases the brakes when the driver uses the brake pedal? |
The service brake system |
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When using the parking brakes or emergency brakes, what type of pressure is being used? |
Spring pressure |
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The air loss rate for a straight truck or bus with the engine off and the brakes applied should not be more than: |
3 psi in one minute |
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Air brakes equipped vehicles must have: |
An air pressure gauge, to show the pressure available for braking |
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Which of the following statements about brakes is true? |
The heavier a vehicle or the faster it is moving, the more heat the brakes have to absorb to stop it |
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Three different systems are found on modern air brake systems; service brakes, parking brakes, and: |
Emergency brakes |
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The purpose of engine retarders is to : |
Help slow the vehicle while driving and reduce brake wear |
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If your vehicle is equipped with an alcohol evaporator, every day during winter you should: |
Check the alcohol level and fill if necessary |
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The air supply pressure gauge shows the driver how much pressure: |
Is available in the air tanks |
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The most common type of foundation brake found on heavy commercial motor vehicles is: |
S-cam drum |
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A straight truck or bus air brake system cannot leak more than how many psi per minute with the engine off and the brakes released? |
2 psi |
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How do you check the free play in manual slack adjusters? |
Park on level ground, chock wheels, release the parking brakes and pull slack adjusters |
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Which of the following answers is most correct about brake use on a long and steep downgrade? |
Use the braking effects of the engine, and when the vehicle speed reaches the "safe" speed, apply brakes firmly until the vehicle speed is reduced to approximately 5 mph below "safe" speed |
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When a failure occurs in the service brake system, the system you need to use to stop the vehicle is the: |
Emergency brake system |
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A combination vehicle air brakes system cannot leak more than how many psi per minute with the engine off and the brakes released? |
3 psi |
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The brake pedal: |
Controls the air pressure applied to operate the brakes |
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During normal operations, the parking and emergency brakes are usually held back by? |
Air pressure |
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Why should you not fan the brakes on and off during long downgrades? |
The short time off the brakes does not allow for brake cooling |
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Modern air brake systems combine three different systems. The system are the service, parking and _____ brake systems. |
Emergency |
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The driver must be able to see a warning before air pressure in the service air tanks falls below _____ psi. |
60 |
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The brake pedal in an air brake system: |
Controls the air pressure applied to the brakes |
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Air brakes takes more time than hydraulic raking because air: |
Takes more time to flow through the lines than hydraulic fluid |
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If your vehicle has an alcohol evaporator, it is there to: |
Reduce the risk of ice in air brake valves in cold weather |
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If your truck had a dual parking control valves, you can use pressure from a separate tank to: |
Release the spring emergency parking brakes to move a short distance |
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To check the free play of manual slack adjusters on S-cam brakes you should park on: |
Level ground, chock wherls, and turn off the parking brakes |
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Of the choices below, the first thing to do when a low air pressure warning comes on is: |
Stop and safely park as soon as possible |
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The air compressor governor controls? |
When air is pumped in to the tanks |
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The braking power of the spring brakes: |
Depends on whether the service brakes are in adjustment |
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All vehicles equipped with air brakes have: |
A supply pressure gauge |
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If you must make an emergency stop, brake so you: |
Can steer and your vehicle stays in a straight line |
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If you do not have automatic tank drains, how often should you drain the oil and water fro. The bottom of compressed air storage tanks? |
At the end of each day of driving |
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The application pressure gauge shows how much air pressure you: |
Are applying to the brakes |
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Your brakes are fading when: |
You have to push harder on the drake pedal to control your speed on a downgrade |
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If your vehicle has an alcohol evaporator, every day during cold weather you should: |
Check the alcohol level and fill the evaporator if needed |
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Why should you drain water from compressed air tanks |
Water can freeze jn cold weather and cause brake failure |
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Your vehicle has a dual air brake system. If low air pressure warning comes on for the secondary system, you should: |
Bring the vehicle to a safe stop and continue only when the system is repaired |
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During normal driving, spring brakes are usually held back by: |
Air pressure |
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In air brake vehicles, the parking brake should be used: |
Anytime the vehicle is parked |
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Emergency stab braking is when you: |
Brake as hard as you can, release the brake when the wheels lock, then push the brakes again when the wheels start rolling |
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A straight truck brake system should not leak at a rate of more than _____ psi per minute with the engine off and the brakes released. |
2 |
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The air loss rate for a straight truck with the engine off and the brakes on should not be more than: |
3 psi in one minute |
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The supply pressure gauge shows how much pressure: |
Is in the air tanks |
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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 |
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Total stopping distance for air brakes is longer that that foe hydraulic brakes due to _____ distance. |
Brake lag |
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The most common type of foundation brake found on heavy vehicles is the: |
S-cam drum brake |
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If the air compressor develops a leak, what keeps the air in the tank? |
The one-way check valve |
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Air brakes take more time to activate than hydraulic brakes because: |
It takes air longer to flow through the lines |
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Why is the stopping distance for air brakes longer that hydraulic drakes? |
Brake lag distance |
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What does the air compressor governor control? |
The air pumped into the sir tanks |
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You should drain water from compressed air tanks because: |
Water can freeze and cause brake failure |
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In cold weather, what should you do to an alcohol evaporator? |
Check and fill the alcohol level |
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In an air brake system, a brake pedal: |
Controls the air pressure applied to the brakes |
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What do all air brake-equipped vehicles have? |
An air supply pressure gauge |
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The air supply pressure gauge indicates: |
The pressure in the air tank |
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The purpose of a dual parking control valves is : |
To release the spring brake Ina an emergency |
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On an long downgrade, how can you tell if your brakes and fading? |
You have to push harder to control your speed |
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How should the free play of manual slack adjusters on S-cam brakes be checked? |
Park on level ground, chock the wheels, turn off the parking brakes |
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The air pressure warning light should come on before the pressure gets below: |
60 psi |
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What are spring brakes held back by? |
Air pressure |
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If there is a leak in the air brake system, the parking or emergency brake can be held in position only by: |
Spring pressure |
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You have a problem if you are testing the service brakes and notice that: |
They have an unusual feel The vehicle pulls to one side Stopping action is delayed |
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The dual air brake system operates on which axle (s)? |
The rear axle The front axle The trailer axle All axles |
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When checking to make sure the spring brakes come on automatically, the parking brake know should pop out when: |
The air pressure falls to between 20 and 40 psi |
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During an emergency stop, how should you brake? |
Brake so you can steer and stay in a straight line |
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During an emergency stop, how should you brake? |
Brake so you can steer and stay in a straight line |
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Why is controlled stab braking better than short, light brake pedal pressure on long downhill grades? |
Light pressure heats up the brakes |
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When a low air pressure warning comes on, you should: |
Stop and park as soon as possible |
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When do you use the parking brake in air barke-equipped vehicle? |
Any time you park |
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If it is not done automatically in your vehicle, how often should you drain your air tanks? |
At the end of each day of driving. |
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What are the three braking systems? |
The service brake and the parking brake and the emergency system |
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What is used to make the brakes work? |
Compressed air |
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What does the air compressor do? |
Pumps air into the air storage tanks |
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What does the air compressor Governor control? |
It controls when the compressor will pump air into the air storage tanks |
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How much compressed air must the storage tanks hold? |
Enough air to allow breaks to be used when the air compressor stops working |
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If oil and water collect in the air tanks what can happen to the brakes? |
The brakes can fail |
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No automatic tank drains - when should you drain the air tank? |
Everyday |
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Where will you find the drain valve for each air tank? |
In the bottom of the tank |
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What are the two types of air tank drains? |
Manually operated... Automatic |
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What is a purpose of an alcohol evaporator? |
It reduces risk of ice and Brake valves and other parts in cold weather |
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How often should you check the alcohol evaporator in cold weather? |
Check the alcohol container and fill up as necessary every day |
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What is a purpose of the safety release valve in the first tank? |
It protects the tank and the rest of the system from too much pressure |
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What are two other names for the brake pedal? |
It can be called the foot valve or treadle valve |
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What can happen if the brake pedal is pressed and released too often? |
Air can be let out of the system faster than the compressor can replace |
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Where are Foundation brakes found? |
At each wheel |
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Where are brake shoes and Linings located? |
Inside each brake drum |
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What happens when a brake lining is pushed against the inside of the drum? |
This causes friction which slows the vehicle and creates Heat |
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On s-cam brakes what happens to the air when you push the brake pedal? |
Air pressure forces out the push rod and moves the slack adjuster |
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Which direction does the s - cam Force brake shoes when brakes are applied? |
It presses them against the inside of the brake drum |
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If the air compressor begins to leak what keeps air in the tanks? |
The one - way check valve |
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What is one kind of gauge that is required for vehicles with air brakes? |
An air pressure gauge |
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What kind of warning signal is required on vehicles with air brakes? |
A low air pressure warning signal |
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What are the three types of low air pressure warning devices? |
A red light... Or a buzzer... Or a wig wag |
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What is used to turn on the stop lights in an air brake system? |
An electric switch that works by air pressure |
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In normal driving parking and emergency brakes are usually held back by? |
Air pressure |
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The effectiveness of the spring brakes are usually held back by? |
Service brakes |
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Why do some buses have a separate air tank to release spring brakes? |
So you can move the vehicle in an emergency |
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What is a dual air brake system? |
Two separate air brake systems with a single set of brake controls |
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What should you look for in checking an air compressor belt? |
Check belts for excessive wear and cracks and tightness |
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What should you do before checking free play in manual slack adjusters? |
Park on level ground and choke the wheels and release parking brakes |
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Combination vehicles: brakes released. The maximum air released? |
Less Than 3 pounds per square inch |
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Single vehicle: brakes released. Maximum air leakage in one minute? |
Less than 2 pounds per square inch |
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After applying brakes fully, maximum air loss in one minute - single vehicles? |
3 pounds per square inch |
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After applying brakes fully Max. Hair loss in one minute - combination vehicle? |
4 pounds per square inch |
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When should the air governor cut out the air compressor? |
At about the manufacturer specified air pressure |
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When making a normal stop when should you push in the clutch? |
Do not push the clutch in until the engine RPMs are down close to idle |
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When making a very quick stop you should break so that you? |
Stay in a straight line and can steer |
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What is another name for controlled braking? |
Squeeze braking |
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What is stab braking? |
Pressing the brake pedal and releasing brakes when Wheels lock up |
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Why does air braking take more time than hydraulic braking? |
Because it takes time for air to flow through the lines to the brakes |