Maine CDL — Air Brakes Practice Test 9

1.You are in the proper low gear on a long downgrade with a 'safe' speed of 50 mph. You braked down to 45 mph and released, and the speedometer now shows 48 mph and rising. What does the manual's technique call for?

Brake again right away and hold light pressure the rest of the way downStay off the brakes until your speed is back up to 50 mph, then brake againShift to a higher gear so the engine stops holding the vehicle backBrake hard enough to come to a full stop, then start again

2.Some air compressors carry their own oil supply. How does the manual say a compressor without one is lubricated?

By alcohol from the evaporatorBy moisture carried in the compressed airBy grease sealed in at the factory, with nothing added laterBy engine oil

3.You will drive a straight truck with hydraulic brakes, but the trailer you tow has air brakes. Is the manual's Air Brakes section meant for you?

No. It applies only when the power unit itself has air brakesNo. Trailer brakes are covered only in the tank vehicles sectionYes. It is for anyone who drives an air-braked truck or bus or pulls an air-braked trailerOnly if the trailer weighs more than the truck does

4.The manual warns about two different outcomes if you keep driving after a low air warning until the spring brakes come on by themselves. Which pairing is right?

Heavily loaded vehicle: a possible skid out of control. Lightly loaded vehicle: a long stopping distanceHeavily loaded vehicle: a long stopping distance. Lightly loaded vehicle or slippery road: a possible skid out of controlHeavily loaded vehicle: no effect. Lightly loaded vehicle: the brakes do not apply at allBoth: the stop is shorter than one made with the foot brake

5.Some vehicles have a dashboard control handle that lets the driver bring the spring brakes on gradually. What does the manual call it?

A relay valveA modulating valveA quick release valveA limiting valve

6.How does the manual's final air brake check have you confirm that the parking brake will hold?

Stop, set the parking brake, and pull gently against it in a low gearSet the parking brake at about 20 mph and time the stopSet the parking brake and stand on the brake pedal with full forcePark on a steep hill, shut off the engine, and see whether the vehicle rolls

7.On Maine's vehicle inspection test, you inspect the brake lines and hoses at an axle. Which of these is NOT one of the things the manual has you inspect?

That the hoses or lines are not leakingThat each line is at least one inch acrossThat no hose or line is cracked, worn or frayedThat couplings and fittings are secure

8.The walk-around check sets a limit on how long a crack in a brake drum may be, measured against the width of the friction area. What does the manual say about brake discs?

Discs may have cracks of any lengthThe same crack limit applies to discsDiscs are not part of the walk-around checkDiscs are held to a one-inch limit regardless of width

9.The manual's check of the governor's cut-out and cut-in points uses the engine at two different speeds. Which pairing is correct?

Idling while pressure builds to cut-out; fast idle while you pump the brake to bring pressure down to cut-inFast idle while pressure builds to cut-out; idling while you pump the brake to bring pressure down to cut-inFast idle for both parts of the checkEngine off for both parts of the check, with the key on

10.When ABS steps in to head off wheel lockup, the electronic control unit lowers brake pressure. According to the manual, how far is the pressure adjusted?

To give the most braking possible without risking lockupTo zero, so the wheels roll freely until the vehicle stopsTo half of whatever the driver is applyingTo a fixed 55 psi at every wheel