Wyoming CDL — Air Brakes Practice Test 7

1.ABS is meant to prevent skids and jackknifes that braking sets off. Which kind of skid do the manual's ABS safety reminders say it will NOT prevent?

A skid from locking the steering wheels under hard brakingA trailer swing set off by overbrakingA jackknife caused by braking too hard on a wet roadA skid from spinning the drive wheels or taking a turn too fast

2.Between 15 and 55 mph on the chart in Wyoming's Section 5, which figure grows faster: driver reaction distance or vehicle braking distance?

Driver reaction distance, which rises from 17 to 390 feetBoth grow at the same rateVehicle braking distance, which rises from 29 to 390 feetNeither; only the total stopping distance changes

3.Section 11M's trailer brake check has you pull forward gently with the trailer parking brake engaged and the tractor's parking brake released. Besides testing the brake, what does the manual say this assists with?

Checking the governor's cut-in pressureChecking slack adjuster stroke on the steering axleChecking the air compressor beltChecking the trailer's coupling connection

4.You are about to pull out in a truck with a dual air system. The primary gauge reads 105 psi and the secondary reads 90 psi. Are you ready to drive?

Yes, because the two readings average close to 100 psiYes, because only the primary system has to reach 100 psiNo, both systems should build to at least 100 psi firstNo, both systems have to reach 150 psi first

5.Your tank pressure dipped to the governor's cut-in level a moment ago and is now climbing through 115 psi. Going by the manual's approximate figures, what is the air compressor doing?

Pumping, and it will keep on until roughly 125 psiResting, because pressure is already above 100 psiResting, because the safety valve has openedPumping, and it will not stop before 150 psi

6.Controlled braking and stab braking start out differently. Which statement gets the difference right?

Controlled braking stops just short of locking the wheels; stab braking applies the brakes all the wayControlled braking applies the brakes all the way; stab braking stops just short of locking the wheelsBoth begin with the lightest pedal pressure that slows the vehicleControlled braking uses the parking brake control; stab braking uses the brake pedal

7.For the parking brake check in Section 11M, you engage the parking brake and gently pull forward against it. What does the manual have you do with the service brake first?

Take your foot off itHold it down firmlyPump it three timesPress it lightly to steady the vehicle

8.Your dual-system truck fails the Step 7 air pressure buildup check, even measured against the manufacturer's specifications. What does the manual tell you to do?

Drive, but keep below 45 mphDrive, and watch the gauges closelyDrain the air tanks and then driveDo not drive until the problem is fixed

9.Compressed air in an air brake system usually carries two things that are bad for the system. Which pair is it?

Alcohol and engine coolantDust and diesel fuelBrake fluid and greaseWater and compressor oil

10.If a driver ignores a low air warning, falling pressure will eventually bring the spring brakes on by themselves. Which pairing of vehicle and risk matches the manual?

Lightly loaded vehicle: no effect, because spring brakes need a full load to applyHeavily loaded vehicle: an abrupt stop, because its weight adds braking forceLightly loaded vehicle: a longer stop than a loaded one, because the springs apply slowlyHeavily loaded vehicle: a long stopping distance, because spring brakes do not act on every axle