True/False
Indicate whether the
statement is true or false.
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1.
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All vehicles with air brakes must have a low air pressure warning signal.
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2.
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When driving, spring brakes are normally held back by the pressure of the
spring.
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3.
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Front wheel braking is good under all weather conditions, so front brake
limiting valves should be left in the “normal” position.
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4.
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A “slack adjuster” is a mechanism on S-cam air brakes designed to
adjust the brake slack so your vehicle stops properly.
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5.
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All vehicles built after 1991 have automatic slack adjusters.
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6.
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To test the low air pressure warning signal, shut the engine off after you have
enough air pressure so that the low air pressure warning signal shuts off. Then, turn on the
electrical power and pump the brake pedal until the air pressure drops below 60 psi and the low air
pressure warning signal comes on.
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7.
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The braking power of the spring brakes depends on the adjustment of the service
brakes.
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8.
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You should be in the proper gear before starting down a hill so that you do not
need to downshift after your speed has built up.
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9.
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The use of brakes on long, steep downgrades is only a supplement to the braking
effect of the engine.
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10.
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Air brakes may fade, but they will never fail completely.
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Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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11.
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Why should compressed air storage tanks for the air brake system be drained of
water?
a. | Water pressure reduces braking effectiveness. | b. | Water in the tanks
can freeze in cold weather and cause brake failure. | c. | Oil and water in the brake lines can mix and
brake the compressor. | d. | None of the
above. |
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12.
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What does the air supply pressure gauge tell you?
a. | How much pressure is in the air lines. | b. | How much pressure is in the brake
drums. | c. | How much pressure is in the air tanks. | d. | How much air pressure you have
used. |
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13.
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A warning signal that can be seen by the driver must come on before the air
pressure in the brake tanks falls below _____ psi (pounds per square inch).
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14.
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You can tell if your vehicle has Antilock Braking Systems (ABS) if:
a. | Your truck tractor was built before 1997. | b. | Your truck stops
very quickly. | c. | There is a yellow ABS malfunction lamp on the instrument panel. | d. | There is a red ABS
indicator on the wheel hub. |
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15.
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Most newer vehicles have two separate air brake systems, known as:
a. | Bi-valve air brakes. | b. | Multi-brakes. | c. | Dual air brake
systems. | d. | None of the above. |
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16.
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To check the movement (or “free play”) of manual slack adjusters on
S-cam air brakes, a driver should:
a. | Park on level ground, turn off the engine and pump the brake pedal to see the slack
adjusters move. | b. | Park on level ground, chock the wheels, apply all spring brakes and measure the slack
gauge. | c. | Park on level ground, chock the wheels and turn off the parking brakes so you can
move the slack adjusters. |
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17.
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To check the slack on automatic slack adjusters, pull hard on each
adjuster. If the slack adjuster moves more than about _______ where the push rod attaches to
it, it probably needs to be adjusted.
a. | 6 inches. | b. | 1 foot. | c. | 3
inches. | d. | 1 inch. |
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18.
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Modern air brake systems combine three different systems. They are the
service brake system, the parking brake system and the ______________ brake system.
a. | Foot. | b. | Drum. | c. | Differential. | d. | Emergency. |
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19.
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On vehicles with air brakes, there must be an air pressure warning signal that
comes on before air pressure in the service brake tanks falls below _______ psi.
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20.
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Which of the following is the first thing a driver should do when a low pressure
warning signal comes on:
a. | Proceed to the closest repair facility. | b. | Continue to your
destination at a reduced speed. | c. | Stop right away and safely park the vehicle so
the problem can be fixed. | d. | Push in the air release
valve. |
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