Maryland CDL — Air Brakes Practice Test 2

1.Truck tractors built with air brakes on or after which date are required to have antilock brakes?

March 1, 1975January 1, 1985March 1, 1997January 1, 2005

2.When making a normal stop in a truck with a manual transmission, when should you push in the clutch?

Wait until engine speed has dropped near idleThe instant you first touch the brake pedalOnly after the vehicle has completely stoppedHalfway through the stop, at highway rpm

3.When the spring brakes finally set on a lightly loaded rig, or on a slick road surface, what extra danger appears?

The trailer brakes let go before the tractor brakes doThe compressor restarts on its own and rebuilds full pressureThe vehicle can slide and you may lose control of itThe steering axle locks itself into a straight-ahead position

4.You are hauling a trailer that has antilock brakes behind a tractor that does not, and the tractor begins to jackknife. What is the right response?

Press the pedal harder to force the tractor back into lineGrab a lower gear and hold steady pressure on the pedalPull the parking brake knob out to straighten the combinationBack off the brake pedal, where it is safe to do so, until you have the rig under control again

5.How is the stab braking method carried out in an emergency stop?

Apply the brakes fully, release when the wheels lock, then reapply fully once they roll againHold steady, light pressure the entire time without releasingPump the brakes rapidly regardless of whether the wheels are rollingApply only the parking brake and steer straight

6.On a vehicle with dual parking control valves and a separate air tank, what limits how you use it to release the spring brakes in an emergency?

It only works when the engine is runningIt can only be used while parked on a downhill gradeIt requires the governor to be at cut-out pressureThe separate tank holds only enough air to release the brakes a few times

7.What does an antilock braking system (ABS) do during a hard brake application?

It keeps the wheels from locking upIt automatically increases braking force to the front axleIt shuts off the service brakes and uses only spring brakesIt raises the tank pressure during braking

8.On a vehicle with an application pressure gauge, needing more and more pressure to hold the same speed is a sign of what?

The governor cutting out too earlyThe tanks holding too much airThe alcohol evaporator running lowThe brakes fading

9.What is the air compressor's job in the brake system?

It bleeds moisture out of the reservoirsIt forces air into the storage tanks or reservoirsIt measures how much pressure remains in the tanksIt automatically applies the parking brakes when you stop

10.What is true of an air tank fitted with a manual drain valve?

It empties the tank by itself while you driveIt only works when the parking brake is setIt comes standard with an electric heaterYou must open it yourself by turning it or pulling a cable