Air Brakes Flashcards
Modern air brake systems combines three different systems. The are the service brakes, the parking brakes and the:
a. S-cam brakes.
b. Drum brakes.
c. Foot brakes.
d. Emergency brakes.
D. Emergency brakes.
Oil and water usually collect in compressed air tanks. If you do not have an automatic tank drain, when should you drain the air tanks?
a. After every working day.
b. After every four hours of service.
c. Once a week.
d. Every other week.
A. After every working day
Why drain water from the compressed air tanks?
a. To keep from fouling the air compressor oil.
b. Water can freeze in cold weather and cause brake failure.
c. The low boiling point of water reduces braking power.
d. Water over cools the compressor.
B. Water can freeze in cold weather and cause brake failure.
Air brake equipped vehicles must have:
a. A supply pressure gauge.
b. An air use gauge.
c. At least two brake heaters.
d. A backup hydraulic system.
A. A supply pressure gauge
What can legally hold a parking or emergency brake in position for a truck, truck tractor or bus?
a. Fluid pressure
b. Air pressure
c. Spring pressure
d. Any of the above
C. Spring Pressure
Air loss in a straight truck or bus should not be more than ____ with the engine off and the brakes on.
a. 1 psi in 30 seconds
b. 1 psi in one minute
c. 2 psi in 45 seconds
d. 3 psi in one minute
D. 3 PSI in one minute
To make an emergency stop with air brakes, using the stab braking method, you should:
a. Pump the brake pedal rapidly and lightly.
b. Brake hard until the wheels lock, and then get off the brakes for as much time as the wheels were locked.
c. Brake as hard as you can, get off the brakes when the wheels lock, get back on the brakes when the wheels start rolling again.
d. Press hard on the brake pedal and apply full hand valve until you stop.
C. Brake as hard as you can, get off the brakes when the wheels lock, get back on the brakes when the wheels start rolling again.
You should know that your brakes are fading when:
a. Pressure on the brake pedal is released and speed increases.
b. You have to push harder on the brake pedal to control your speed on a downgrade.
c. The brake feels spongy when pressure is applied.
d. Less pressure is needed on the brake pedal for each stop.
B. You have to push harder on the brake pedal to control your speed on a downgrade.
To check the free play of manual slack adjusters on s-cam brakes you should:
a. Park on level ground, chock the wheels, and release the parking brakes.
b. Stop on level ground and apply the parking brakes.
c. Park on level ground and drain off air pressure before adjusting.
d. Park on a slight grade, release the parking brake, apply the service brakes, and check for vehicle movement.
A. Park on level ground, chock the wheels, and release the parking brakes.
If the air compressor should develop a leak, what keeps the air in the tanks?
a. The tractor protection valve
b. The emergency relay valve
c. The one way check valve
d. The air compressor
C. The one way check valve
When driving down a long steep hill you should:
a. Use stab braking.
b. Begin braking when you are 10 M.P.H. above your safe speed.
c. Release the brake when you are 5 M.P.H. below your
d. Use the trailer brakes.
C. Release the brake when you are 5 M.P.H. below your
The brake system that applies and releases the brakes when the driver uses the brake pedal is the:
a. Service brake system.
b. Emergency brake system.
c. Parking brake system.
d. None of the above.
A. Service brake system
The most common type of foundation brakes found on heavy vehicles is the:
a. Disc brakes
b. Wedge drum
c. S-cam drum
d. None of the above
B. S-cam drum
Vehicles with air brakes must have:
a. At least two air tanks.
b. An air pressure gauge to show the pressure available for braking.
c. An air pressure gauge, to show air used by the brake chambers for braking.
d. None of the above.
B. An air pressure gauge to show the pressure available for braking.
The driver must be able to see a warning that is given before air pressure in the service air tanks falls below:
a. 80 psi
b. 40 psi
c. 20 psi
d. 60 psi
D. 60 psi