Air Brakes Practice Questions
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- They should never be used
- As the only method of controlling speed
- As much as possible
- Sparingly and intermittently
From The CDL Manual
Proper Braking Technique —
Remember, the use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. Once the vehicle is in the proper low gear, the following is the proper braking technique:
- Apply the brakes just hard enough to feel a definite slowdown.
- When your speed has been reduced to approximately 5 mph below your “safe” speed, release the brakes. (This brake application should last about 3 seconds.)
- When your speed has increased to your “safe” speed, repeat steps 1 and 2.
- Free coasting
- Swerving gently side-to-side
- Through the braking effect of the engine
- With the service brake
From The CDL Manual
Proper Braking Technique —
Remember, the use of brakes on a long and/or steep downgrade is only a supplement to the braking effect of the engine. Once the vehicle is in the proper low gear, the following is the proper braking technique:
- Apply the brakes just hard enough to feel a definite slowdown.
- When your speed has been reduced to approximately 5 mph below your “safe” speed, release the brakes. (This brake application should last about 3 seconds.)
- When your speed has increased to your “safe” speed, repeat steps 1 and 2.
- Coast out-of-gear until the vehicle stops
- Immediately engage the emergency brake
- Stop and park your vehicle as soon as it is safe to do so
- Pump the brake pedal furiously
From The CDL Manual
Low Air Pressure —
If the low air pressure warning light comes on, stop and safely park your vehicle as soon as possible. There might be an air leak in the system.
- 120 psi
- Between 20 to 45 psi
- 100 psi
- 60 psi
From The CDL Manual
Controlled braking is possible only while enough air remains in the air tanks. The spring brakes will come on when the air pressure drops into the 20 to 45 psi range.
- When you need to stop quickly
- Any time you park the vehicle
- Only in an emergency
- Only when parked on an incline
From The CDL Manual
Parking Brakes —
Any time you park, use the parking brakes, except as noted. Pull the parking brake control knob out to apply the parking brakes. Push it in to release them. The control will be a yellow, diamond-shaped knob labeled “parking brakes” on newer vehicles.
- First thing in the morning
- If the brakes are very hot
- In the desert
- On flat ground
From The CDL Manual
Do not use the parking brakes if the brakes are very hot (i.e., from just coming down a steep grade), or if the brakes 69 are very wet in freezing temperatures. If the brakes are used when very hot, they can be damaged by the heat. If they are used in freezing temperatures when the brakes are very wet, they can freeze so the vehicle cannot move. Use wheel chocks to hold the vehicle. Let hot brakes cool before using the parking brakes. If the brakes are wet, use the brakes lightly while driving in a low gear to heat and dry them.
- Use a hair dryer
- Apply the brakes lightly while driving in a low gear
- Park in the sun
- Speed up to 30 mph and apply the brakes very hard
From The CDL Manual
If the brakes are wet, use the brakes lightly while driving in a low gear to heat and dry them.
- Whenever your dispatcher tells you to
- Every 1000 miles
- When the brakes start fading
- At least at the end of every day
From The CDL Manual
If your vehicle does not have automatic air tank drains, drain your air tanks at the end of each working day to remove moisture and oil. Otherwise, the brakes could fail.
- Round and yellow
- Red and octogonal
- Round and blue
- Diamond and yellow
From The CDL Manual
See Figure 5-4, Page 69 of the CDL manual
- Blue and round
- Red and round
- Yellow and diamond-shaped
- Red and octogonal
From The CDL Manual
See Figure 5-4, Page 69 of the CDL manual
- Blue and round
- Yellow and diamond-shaped
- Yellow and round
- Red and octogonal
From The CDL Manual
See Figure 5-4, Page 69 of the CDL manual
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