Ohio CDL — Air Brakes Practice Test 1

1.What is the "controlled braking" method for an emergency stop?

Braking as firmly as possible short of locking the wheels, keeping steering inputs smallPressing the pedal all the way and releasing when the wheels lockPumping the pedal in a steady rhythm the whole stopUsing only the trailer brakes to slow down

2.How do spring brakes actually hold a parked truck in place?

Air pressure keeps a steady force on the brake chambersAn electric motor holds the shoes against the drumsA hydraulic lock traps fluid in the calipersStrong springs clamp the brakes on once the air is released

3.Once the governor has stopped the compressor, tank pressure must fall to about what level before the compressor is allowed to start pumping again (the "cut-in" point)?

About 60 psiAbout 125 psiAbout 100 psiAbout 150 psi

4.When the low-air warning first lights up and the buzzer sounds while driving, what does the manual say to do?

Keep driving until the spring brakes apply on their ownPull over and stop safely at once, while air still remains to work the brakesPump the brake pedal to build the pressure back upPull the parking brake control to lock the wheels immediately

5.While you are driving, the low-air-pressure warning suddenly lights up. What should you do?

Speed up to reach the next exit before the brakes failPump the brakes hard to try to rebuild pressurePull the parking brake knob to stop fasterStop and safely park as soon as possible, because there may be an air leak

6.A visible low-air warning is required on air-brake vehicles. It must come on before tank pressure drops below what level?

Below 55 psiBelow 40 psiBelow 60 psiBelow 20 psi

7.How do you set the parking brakes with the diamond-shaped control knob?

Pull the knob out to apply them and push it in to releasePush the knob in to apply and pull it out to releaseTurn the knob a quarter turn clockwiseHold the knob down while pressing the brake pedal

8.Before checking the slack adjusters by hand, what should you do first?

Set the parking brakes and leave the engine runningDrain both air tanks completelyApply the foot brake and hold it downPark on level ground, chock the wheels, and release the parking brakes

9.Before you drive a rig equipped with a dual air brake system, how much pressure should the compressor build in both the primary and secondary systems?

At least 55 psiAt least 125 psiAt least 100 psiAt least 150 psi

10.On an s-cam brake, what happens when you press the brake pedal?

The cam pulls the shoes away from the drum to release themThe cam clamps a rotor between two lining padsThe cam rotates and forces the shoes apart against the inside of the drumThe cam pushes a wedge between the ends of the shoes