Minnesota CDL — Air Brakes Practice Test 8

1.What most commonly causes air brakes to fade?

Draining the tanks too oftenOverusing the service brakes instead of the engine to slow down, which builds excessive heatRefilling the alcohol evaporator too frequentlySetting the parking brake while moving

2.Why shouldn't you set the parking brakes when the brakes are very wet in freezing temperatures?

The water raises tank pressure dangerouslyThe wig wag will not resetThe brakes could freeze so the vehicle cannot moveThe alcohol evaporator will overflow

3.What happens as the brake shoes and linings press against the drum to slow the vehicle?

The air in the tanks is rechargedThe governor lowers its cut-out pressureThe slack adjusters tighten automaticallyFriction slows the vehicle and produces heat

4.What should you always do before leaving your vehicle unattended?

Drain the alcohol evaporatorRelease the spring brakesPump the brake pedal several timesSet the parking brakes or chock the wheels

5.What does an antilock braking system (ABS) do?

It shortens your stopping distance in every situationIt replaces the need for a parking brakeIt keeps the wheels from locking up during hard brakingIt automatically drains moisture from the tanks

6.You are stopping a tractor-trailer on which every axle has a working antilock system. What braking method should you use?

Pump the pedal repeatedly so the computer has time to cycleReach for the trailer hand valve first and finish with the pedalStay off the service brakes entirely and let the engine slow the rigBrake the way you always have, applying only the force the stop calls for

7.What is true about using the front wheel brakes on a commercial vehicle?

They should be shut off on any wet or icy roadFront wheel braking is helpful under all driving conditionsThey must be disconnected below 55 psiThey cause skids on ice more often than they help

8.What is 'controlled braking' during an emergency stop?

Pumping the pedal rapidly to keep air in the tanksLocking the wheels and steering hardLetting the ABS do all the braking for youBraking as hard as you can without locking the wheels, using only small steering movements

9.If the air compressor has its own separate oil supply, what should you do before driving?

Check the compressor's oil levelDrain the alcohol evaporatorLoosen the drive belt slightlyBleed the primary air tank

10.Why can a heavily loaded vehicle take a long distance to stop once the spring brakes come on?

The spring brakes do not act on all of the axlesThe service brakes lock every wheel at onceThe load raises the governor cut-out pressureThe ABS shuts the brakes off under heavy loads