Michigan CDL — Air Brakes Practice Test 10

11.Which style of foundation brake is found most often on air brake vehicles?

The wedge brakeThe s-cam drum brakeThe air-operated disc brakeThe hydraulic caliper brake

12.What is the job of an alcohol evaporator in an air brake system?

To cut the chance of ice forming in the brake valves during cold weatherTo push tank pressure above 150 psiTo replace the water drained from the tanksTo keep the compressor drive belt from slipping

13.On a truck that has a dual air brake system, how much pressure should the compressor build in both halves before you drive off?

60 psi85 psi125 psi100 psi

14.Vehicles built since which year come with automatic slack adjusters?

1975198519981994

15.Which statement best describes what antilock brakes actually do for you?

They shorten your stopping distance on every surfaceThey replace the need for a service brake systemThey let you drive faster on iceThey keep the wheels from locking during hard braking so you stay in control, though they may not shorten stopping distance

16.How do you test that the parking brake will hold?

Set it, then gently tug against it in a low gear to see if it keeps the vehicle from movingRev the engine to governor cut-out with the brake offDrain the tanks and watch the gaugeApply the foot brake while rolling at 5 mph

17.You find you must keep raising application pressure to hold a steady speed. What is the application pressure gauge warning you about?

The compressor is over-pressurizing the tanksThe parking brakes are draggingThe brakes are fading, so you should slow down and drop to a lower gearThe alcohol evaporator has run empty

18.Why is it important to empty the air tanks of the moisture that collects inside them?

Water improves braking friction and must be measuredDraining the tank refills the alcohol evaporatorCollected water can freeze in cold weather and knock out the brakesThe water is needed to lubricate the s-cam

19.Suppose the low-pressure warning activates while you are driving. What is the safest thing to do?

Speed up to reach your destination before the air is goneIgnore it unless the spring brakes applyStop and safely park as soon as possible, because there may be an air leakPump the pedal to raise the pressure back up

20.In a dual air system at operating rpm, how long should it take the pressure to climb from 85 up to 100 psi?

3 minutes90 seconds2 minutes45 seconds