New Hampshire CDL — Air Brakes Practice Test 6

1.Two trucks both have alcohol evaporators. Truck A's air tanks have manual drain valves; Truck B's have automatic drain valves. Under the alcohol evaporator passage, which truck still needs its tanks drained by the driver every day?

Truck B onlyBoth trucksNeither truck, because the alcohol removes the waterTruck A only

2.For the front of the vehicle and engine area on the vehicle inspection test, the manual explains why you look for air leaks. What could an air leak point to?

Tires that have been overinflatedA fuel tank cap that is missingCoolant that is too cold to circulateA failing component in a spot that is not easy to inspect, such as the air compressor

3.Why does the manual say an air brake system includes a stop light switch?

Because the low air warning needs a second lampBecause the compressor must shut off during brakingBecause the parking brake knob needs a dash indicatorBecause drivers behind you have to be warned when you brake

4.Wedge brakes and S-cam brakes use different mechanisms. What does the manual's description show they have in common?

Both force brake shoes against the inside of a brake drumBoth use a power screw to clamp a rotorBoth rely on a caliper with lining padsBoth are self-adjusting on every vehicle

5.The safety relief valve is usually set to open at a fixed pressure. Using the manual's usual numbers, about how far above the governor's cut-out level is that?

About 5 psiAbout 25 psiAbout 50 psiAbout 95 psi

6.Your truck has a manual-reset wig wag. With system pressure still at 45 psi, you push the arm up out of your line of sight. What does the manual say will happen?

The arm locks in place and the warning is canceledThe spring brakes releaseThe arm will not stay put until pressure is back above 55 psiThe compressor governor cuts out

7.A straight truck's air leakage is checked both ways with the engine off. With the brakes released, the gauge falls 2.5 psi in one minute. With the foot brake held fully down, it also falls 2.5 psi in one minute. How do those results compare with the manual's limits for a single vehicle?

Within the limit on both testsToo much loss on both testsToo much loss with the brakes released, but within the limit with the foot brake appliedWithin the limit with the brakes released, but too much with the foot brake applied

8.The Air Brakes section spreads its extra checks across the seven-step inspection. Which of these is done in the Step 7 final air brake check, not in the Step 5 walk-around?

Pulling on the slack adjustersLooking over brake drums and liningsChecking the air hoses at the brake chambersTiming the air leakage rate

9.After the low air pressure warning comes on, how long does the manual say controlled braking stays possible?

For as long as the engine keeps runningUntil the ABS malfunction lamp lightsFor exactly one more full brake applicationOnly while enough air is left in the tanks

10.Rig 1 has ABS on the tractor only. Rig 2 has ABS on the trailer only. Which statement matches what the manual says each rig gains under braking?

Rig 1's trailer is less likely to swing out; Rig 2 should keep steering control and is less likely to jackknifeRig 1 gains nothing; only Rig 2 has more controlRig 1 should keep steering control and is less likely to jackknife; Rig 2's trailer is less likely to swing outBoth rigs stop in half the distance, and neither can skid