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CDL Air Brakes 2

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  • Why should you drain water from compressed air tanks?
    Water can freeze in cold weather and cause brake failure.
    Water low boiling point reduces braking power.
    To keep from fowling the air compressor oil.
  • If you are driving down a steep downgrade and have reached your safe speed of 40 mph, you would apply this service brake until your speed dropped to ___mph.
    30
    35
    25
  • Excessive heat caused by using your brakes too often can also cause:
    Brake to fade or fail.
    Modulated control valve to wear out.
    Brake linings to split up.
  • If your vehicle has an alcohol evaporator, it is there to:
    Reduce the risk of icing in air brake valves in cold weather
    Eliminate the need for daily tank draining.
    Boost tank pressure, the same way turbocharges boost engines
  • Your brakes are fading when:
    Less pressure is needed on the brake pedal for each stop.
    The brake pedal feels spongy when you apply pressure.
    You have to push harder on brake pedal to control speed
  • The air compressor governor controls:
    When air is pumped into the air tanks.
    Air pressure applied to the brakes.
    The speed of the air compressor.
  • The use of brakes on a long and steep downgrade under normal conditions is only a supplement to:
    The use of the front brakes limiting valve.
    The braking effect of the engine.
    Use of spring brakes.
  • If the air compressor should develop a leak, what keeps the air in the tanks?
    The tractor protection valve.
    The one-way check valve.
    The emergency relay valve.
  • What happens when your brake drums get very hot?
    They contract.
    They start to smoke.
    They expand.
  • Which of these is NOT a proper time to apply the parking brakes?
    If you are going to test the parking
    If you will be stopping for only one hour.
    If the brakes are very hot
  • The braking power of the spring brakes:
    Depends on the brakes being in adjustment.
    Is not affected by the condition of the service brakes.
    Can only be tested by highly trained brake service people.
  • To check the free play of manual slack adjusters of S-cam brakes, you should park on:
    Level ground, drain air pressure before checking adjustment
    Level ground, chock the wheels & release the parking brakes
    Level ground, apply parking brakes, then apply service brake
  • Stab braking: (#50)
    Apply your brakes all the way. Release the brakes when wheels lock up. As soon as the wheels start rolling, apply the brakes fully again.
  • The most important thing to do when a low air pressure warning comes on is:
    Downshift.
    Up-shift.
    Stop and safely park as soon as possible.
  • If air pressure is not built up within the correct amount of time, then:
    You should be ready to use your parking brakes to stop.
    Air pressure may drop while driving, requiring emergenc stop
    The alcohol container may be low.
  • Modern air brakes combine three different systems. They are the service, the parking, and the ____ brakes.
    Emergency
    Drum
    Foot
  • The proper use of the brakes when going down a long steep grade after selecting a proper gear, is about ___ below the posted speed and release your brake.
    15 mph
    10 mph
    5 mph
  • If your truck has a dual air brake system, and one of the systems is low on pressure:
    The manual slack adjusters on S-Cam brakes aren't set proper
    The brake drums will not be fully operational.
    Either the front or rear brakes will not be fully functional
  • If the spring brakes are on, when should you push the brake pedal?
    Only when driving downhill.
    Never.
    Only on a slippery road.
  • The ___ shows how much pressure is in the air tanks.
    oil gauge
    supply pressure gauge
    air usage gauge
  • If you must make an emergency stop, you should brake so you:
    Can steer hard while braking hard.
    Can steer and keep your vehicle in a straight line.
    Use the hand brake first.
  • What can legally hold a parking or emergency brake in position for a truck, truck tractor, or bus?
    Fluid pressure.
    Spring pressure.
    Air pressure.
  • The safety valve discharges automatically at the pressure of:
    150 psi
    50 psi
    100 psi
  • With air brake vehicles, the parking brakes should be used:
    Any time when vehicle is parked.
    As little as possible.
    To hold your speed when going downhill.
  • The supply pressure gauge shows how much pressure:
    Is going to the brake chamber.
    You have used in this trip.
    Is in the air tanks.
  • When is it OK to leave your truck unattended without applying the parking brakes and chocking the wheels?
    Never.
    If you are conducting a pre-trip inspection.
    If you are only away for a few minutes.
  • The parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away, like:
    Spring pressure.
    Hydraulic pressure.
    Air pressure.
  • Air braking takes more time than hydraulic braking because:
    Air brakes use different brake drums.
    Air takes more time to flow thru lines than hydraulic fluid
    Air brakes require heavier return springs.
  • What is a “Wig Wag”?
    A mechanical arm that signals low air pressure.
    A spring mount for hair pieces.
    Part of the stop light system.
  • When brakes are applied, the brake shoes will press against the:
    S-cam.
    Slack adjuster.
    Brake drum or disc.
  • If you don’t have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks?
    At the end of each day of driving.
    Once a week.
    After every four hours of service.
  • It’s not safe to drive a vehicle that has brake drums with cracks that are longer than _____ of the width of the friction area.
    1/4
    1/8
    1/2
  • The stop light switch:
    Tells you when the air brake system is low on air pressure.
    Turns on the brake lights when you put on the air brakes.
    Tells you when you need to use your emergency brakes.
  • To test air service brakes you should:
    Brake slowly while slowly moving backward.
    Brake firmly while slowly moving forward.
  • The safety valve reduces pressure at ____ psi.
    150
    50
    100
  • In ideal conditions, a truck or bus with air brakes going at 55 mph would require the stopping distance of how many feet?
    From 100 to 300 feet.
    More than 300 feet.
    Less than 100 feet.
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