Wisconsin CDL — Air Brakes Practice Test 10

1.What is a 'wig wag' low-pressure warning device?

A buzzer that sounds when the parking brake releasesA gauge needle that flutters as the compressor loadsA light that flashes during the ABS bulb checkA mechanical arm that drops into your view when pressure falls below 60 psi

2.Which sequence describes the stab braking method?

Press lightly and hold steady until the vehicle stopsPump the pedal quickly the whole way down the roadApply partway, then ease off little by littleApply fully, release when the wheels lock, then reapply fully once they roll again

3.You brake hard on a slick road in a truck built without ABS. What is the result if the wheels on the steering axle lock up?

The trailer brakes release by themselvesYou can no longer steer the vehicleThe spring brakes apply automaticallyThe air compressor stops pumping

4.For a combination vehicle, what is the most air pressure that may be lost in one minute during the leakage test?

1 psi2 psi3 psi4 psi

5.On a vehicle equipped with one, needing more and more application pressure to hold a steady speed points to what?

The compressor is cutting out too soonThe tanks are overfilledThe brakes are fading, so slow down and select a lower gearThe alcohol evaporator has run dry

6.If you keep driving after the low air warning comes on, what limits your braking?

The parking brake locks the steering wheelControlled braking works only while air remains, and the spring brakes set at 20 to 45 psiThe compressor overheats and quitsThe stop lamps stop working first

7.If your tanks have manually operated drain valves, how often should you drain them?

Only when the low-pressure warning comes onAt the end of every day you driveAbout once a monthOnly before a long downhill grade

8.Why should you avoid pressing and releasing the brake pedal for no reason?

It overheats the brake linings almost at onceIt makes the governor cut out earlyIt can bleed air off faster than the compressor can replace it, and low pressure means no brakesIt pushes oil from the compressor into the tanks

9.What is a dual air brake system?

One air system feeding two separate pedalsA system that switches between air and hydraulic brakingTwo compressors that share a single air tankTwo separate air brake systems run by one set of controls

10.What effect does pushing the brake pedal down harder have?

It sends less air to the brakes to prevent lockupIt applies more air pressure to the brakesIt sets the parking brakesIt has no effect once the shoes touch the drums