Connecticut CDL — Air Brakes Practice Test 9

1.The governor lets the compressor begin pumping again once tank pressure falls to what level?

Around 55 psiAround 100 psiAround 125 psiAround 150 psi

2.When should you NOT set the parking brakes?

When the brakes are very hot from a steep grade, or very wet in freezing temperaturesWhenever the vehicle is fully loadedAny time you park on level groundOnly when the engine is still running

3.What does a 'wig wag' low-pressure warning do?

It sounds a horn outside the cabIt automatically drains the tanksIt drops a mechanical arm into the driver's view when pressure is lowIt flashes the brake lights to the rear

4.Your brakes are soaked and the temperature is below freezing. How should you dry them out?

Set the parking brakes and leave them on overnightPour warm water over each brake drumDrive in a low gear while pressing the brakes lightlyRev the engine until the tanks reach cut-out pressure

5.Why is it important to drain the water that collects in the air tanks?

Water improves braking friction if left inIn cold weather the water can freeze and cause the brakes to failWater raises the governor cut-out pressureDraining water recharges the alcohol evaporator

6.When checking a slack adjuster on an s-cam brake, how much movement suggests it needs adjustment?

Any movement at allMore than roughly one inch of movement at the push-rod attachment pointMore than three inchesLess than a quarter inch

7.In a dual air brake system, what happens if one of the two systems becomes very low on pressure?

One end of the rig, front or rear, loses full braking power, so stops take longerBoth systems shut down at onceThe parking brakes automatically releaseStopping distance is unaffected

8.On a tractor or straight truck, spring brakes come fully on when air pressure drops into what range?

55 to 80 psi80 to 100 psi100 to 125 psi20 to 45 psi

9.What is the main function of the air compressor?

It cools the brake drums after repeated stopsIt measures how much pressure reaches the brakesIt pumps air into the storage tanksIt releases the spring brakes for parking

10.How do you park a vehicle whose spring brakes are set by a modulating control lever?

Leave the lever centered and rely on the service brakesPull the lever halfway back, then shut the engine offChock the wheels and leave the lever in the off positionPush the lever through its whole travel and hold it there with the locking device