Delaware CDL — Air Brakes Practice Test 9

1.Your combination vehicle has ABS on just one axle. What does the manual say about that?

ABS on a single axle makes braking worseIt works only if the trailer has ABS as wellYou must switch to stab braking for every stopEven that gives you more control during braking

2.What does the manual mean by 'brake lag'?

The delay between pushing the pedal and the brakes actually workingThe distance covered while you decide whether to brakeThe loss of braking power when drums overheatThe time the compressor needs to refill the tanks

3.You pass the air brakes knowledge test, then take your Delaware skills exam in a truck that has no air brakes. What goes on your CDL?

A Z restriction, limited to air over hydraulic brakesAn E restriction, automatic transmission onlyNothing; passing the knowledge test is enoughAn L restriction barring you from CMVs with any type of air brakes

4.Each time you let up on the brake pedal, what happens to the air in the system?

It all flows back into the storage tanks, so pressure stays the sameIt is trapped in the brake chambers until the next stopSome of it escapes, so tank pressure falls until the compressor replaces itIt is routed to the spring brakes to hold them off

5.Once you are in the right low gear on a long downgrade, how hard does the manual say to press the brakes each time you apply them?

As hard as possible, until the wheels lockSo lightly that your speed does not changeFirmly enough that you can clearly feel the vehicle slowingWith full pressure, held all the way to the bottom

6.For the L restriction on a CDL, what does the manual count as 'air brakes'?

Any brake system that works wholly or partly on the air brake principleOnly systems that run entirely on airOnly the spring brakesOnly the brakes on a trailer

7.A modulating control valve lets the driver bring the spring brakes on gradually. Why does the manual say it works that way?

It gives the driver a controllable way to stop with the spring brakes after a service brake failureIt lets the parking brakes be set without using any airIt gives the compressor time to cut inIt makes the trailer brakes apply ahead of the tractor brakes

8.During the emergency brake test on Delaware's inspection test, your vehicle has valves that do not pop out by design. How do you tell that the parking or emergency brakes have applied?

Watch for the ABS lamp to lightWait for the low air buzzer to go quietCheck that the governor cuts inListen for air discharging from the air system

9.How many brake chambers may a wedge brake have?

One or twoAlways exactly oneNone, because wedge brakes do not use brake chambersAlways four

10.Your low air warning is on, and you are driving a lightly loaded truck on a slippery road. What does the manual warn can happen if you keep going until the spring brakes apply on their own?

The truck may skid out of controlThe spring brakes will not apply at allThe compressor will be damagedThe ABS will lock the steering