Alabama CDL — Air Brakes Practice Test 10

1.Which type of foundation brake is the most common on vehicles with air brakes?

The wedge brakeThe disc brakeThe s-cam drum brakeThe band brake

2.In which situation does the manual allow a driver to push the brake pedal all the way down for an emergency stop?

Any time the road surface is wet or covered with iceWhenever the vehicle happens to be running emptyWhen the truck or combination has antilock braking working on all of its axlesOnly when the trailer by itself carries an antilock system

3.You will be stepping away from your truck for only a minute or two. What has to happen first?

Nothing extra is needed for such a brief absenceLeaving the transmission in a low gear is enough by itselfLet the engine idle so the tanks stay chargedSet the parking brakes, or chock the wheels, before you walk away

4.When using the 'controlled braking' method in an emergency, how hard should you press the brakes?

As hard as you can without locking the wheelsOnly lightly, so the wheels never slowHard enough to lock the wheels and hold themIn quick full-pressure pulses only

5.In the service brake check you creep ahead at roughly five mph and press the pedal firmly. What are you looking for?

A drop in the engine oil pressure readingAir escaping from the alcohol evaporatorThe governor cutting the compressor out earlyThe truck tugging to one side, an odd feel, or a late stop

6.What is the purpose of an alcohol evaporator in an air brake system?

It cools the compressor during hard brakingIt lowers the risk of ice forming in the brake valvesIt replaces the need to drain the tanksIt boosts the pressure the compressor can build

7.While holding a steady speed you notice you must keep increasing the application pressure. What does this most likely mean?

The brakes are fading and you should slow down and use a lower gearThe compressor has switched to its backup settingThe air tanks are fully drained of moistureThe spring brakes are about to release on their own

8.When is it best NOT to set the parking brakes?

When the brakes are very hot, or very wet in freezing weatherWhenever the vehicle is parked on level groundAny time the trailer is loadedWhen the air tanks are fully charged

9.For a vehicle with air brakes, total stopping distance is made up of which four parts?

Perception, reaction, cornering, and coasting distanceFollowing, merging, braking, and reaction distancePerception, reaction, brake lag, and braking distanceIdle, cut-in, cut-out, and braking distance

10.The governor lets the compressor start pumping again once tank pressure falls to what approximate level (the cut-in point)?

About 100 psiAbout 20 psiAbout 45 psiAbout 150 psi