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The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like
B. spring pressure
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A straight truck or bus air brake system should not leak at a rate of more than ____ psi per minute with the engine off and the brakes released
B. 2
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Your vehicle has a dual air brake system. If a low air pressure warning comes on for the secondary system, you should
A. bring the vehicle ato a safe stop and continue only when the system is fixed
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If your vehicle has an alcohol evaporator, it is there to
D. reduce the risk of ice in air brake valves i cold weather
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Air braking takes more time than hydraulic braking because air
B. takes more time to flow through the lines than hydraulic fluid
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The brake pedal in air brakes system
C. controls the air pressure applied to put on the brakes
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If your truck or bus has dual parking control valves, you can use pressure from a separate tank to
A. release the spring emergency/parking brakes to move a sort distance
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Modern air brake systems combine three different systems. They are the service, parking , and the _____ brakes
A. emergency
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To check the free play of manual slack adjusters on S-cam brakes, you should park on
B. level ground, chock the wheels, 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
A. stop and safely park as soon as possible
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The air compressor governor controls
d. WHEN AIR IS PUMPED INTO THE AIR TANKS
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The braking power of the spring brakes
C. depends on the service brakes being in adjustment
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All air brake equipped vehicles have
C. a supply pressure gauge
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If you must make an emergency stop, brake so you
C. can steer and your vehicle stays in straight line
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The application pressure guage shows how much air pressure you
C. are applying to the brakes
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If you do not have automatic tank drains, how often should you drain the oil and waer from the bottom of the compressed air storage air tanks
B. at the end of each day of driving
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You should know that your brakes are fading when
A. you have to push harder o the brake pedal to control your speed on a downgrade
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If your vehicle has an alcohol evaporator, every day during cold weather yo should
D. check and fill the alcohol level
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Why drain water from compressed air tanks
B. water can freeze in cold weather and cause brake failure
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To test air service brakes, you should brake firmly when moving slowly forward. The brakes are ok if you notice
D. none of the above
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For long downhill grades, experts recommend using a low gear and light, steadypedal pressure instead of on-again braking. why?
D. all of the above
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The driver must be able to see a waring before air pressure in the service air tanks fall below ___ psi
C. 60
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During normal driving, spring brakes are ussually held back by
B. air pressure
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In air brakes vehicles, the parking brakes should be used
B. any time the vehicle is parked or unattended
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Emergency stab braking is when you
D.Bake as hard as you can, release the brakes when the wheels lock, put on the brakes again when the wheels start rolling
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The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than
D. 3 psi in one minute
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The supply pressure gauge shows how much pressure
B. 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
B. service
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Your truck or bus has a dual air brake system. If a low air pressure warning come on for only one system, what should you do
D. stop right away and safely park. continue only after the system is fixed
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Total stopping distance for air brakes is longer than that for hydraulic brakes due to ____ distance
C. brake lag
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The most common type of foundation brake found on heavy vehicles is the
C. S-cam drum
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Parking or emergency brakes of trucks and buses can be legally held on by ____ pressure
A. spring
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If the air compressor develops a leak, what keeps the air in the tanks
C. the one-way check valve
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