1. The modulating control valve allows you to control:
Spring brakes.
Front brakes.
Amount of air pressure in the brake system.
2. A slack adjusters freeplay needs to be adjusted if it is more than about____ how many inches when you pull hard on it?
one fourth inch
one half inch
one inch
3. If your vehicle has an alcohol evaporator, it is there to:
Eliminate the need for daily tank draining.
Boost tank pressure the same way that turbocharges boost engine.
Reduce the risk of icing in air brake valves in cold weather.
4. The air compressor governor controls:
The speed of the air compressor.
Air pressure applied to the brakes.
When air is pumped into the air tanks.
5. If air pressure is not built up within the correct amount of time, then:
You should be ready to use your parking brakes to help stop.
The alcohol container may be low.
Your air pressure may drop too low during during T driving, requiring an emergency stop.
6. How should you check that your service brakes are working properly?
Park on slight grade, drain off air pressure,set parking brake and check to the movement.
Park on a level ground, chock the wheels,engage the parking brakes when you have the correct amount of air pressure to do so and shut the engine off.
Park on level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at about 5 mph. Then apply the brakes firmly using the brake pedal.
7. Under normal conditions in order to engage the parking brakes driver:
Turn off the engine.
Let the air out of air brake system.
Be sure that the air brake system is fully pressurized.
8. To check the free play of manual slack adjusters of S-cam brakes, you should park on:
Level ground, chock the wheels and release the parking brakes.
Level ground and apply the parking brakes, then apply service brakes.
Level ground and drain off air pressure before checking the adjustment.
9. Parking or emergency brakes of trucks and buses can be legally held on by____pressure.
10. With air brake vehicles, the parking brakes should be used:
Whenever you leave the vehicle unattended.
As little as possible.
Only during pre and post-trip inspections.
11. The most important thing to do when a low air pressure warning comes on is:
Upshift.
Downshift.
Stop and safely park as soon as possible.
12. Emergency controlled braking is when you:
Apply the brakes as hard rd as as you you can can without without locking the wheels.
Brake as hard as you can, release the brakes B when wheels locking, brakes back on again when the wheels start rolling.
Apply the hand valve for one second, then push hard on the brakes.
13. Any time you park, use the parking brakes, except:
If the brakes are very hot (e.g., after just coming down grade a steep grade).
If you are going to test the parking brake make sure that it holds the vehicle.
If you will only be stopped for less then one hour.
14. You have a major leak in the service line and put on the brakes. Service air pressure will escape and cause the:
trailer tank pressure to be lost.
tractor spring brakes to lock on.
trailer emergency brakes s to come on.
15. The air brake lag distance at 55 mph on dry pavement adds about___feet.
16. If you are driving down a steep downgrade and you have reached your "safe" speed of 40 mph, you would apply the service brakes until your speed drops to___ mph.
17. If your truck has a properly functioning dual air brake system and minimum size air tanks the air pressure should build up from 85 to 100 psi within how many seconds?
18. All air brake equipped vehicles have:
A supply pressure gauge.
An air usage gauge.
A backup hydraulic system.
19. The most common type of foundation brake found on heavy vehicles is the:
Wedge drum.
S-cam drum.
Disc brake.
20. Your truck has a dual air system and one of the system loses its pressure. What will happen?
Brake drums will not be fully pressurized.
The manual slack adjusters of the S-cam brakes will not be set properly.
Either the front or back brake will not be fully operational.
21. Which of these is NOT a proper time to apply the parking brakes?
To brake vehicle very hard, in other word.
To use parking brakes if you park for less than one hour.
If you are going to use the parking brakes C you need to make sure that they will hold the vehicle.
22. If the spring brakes are on, when should you push the brake pedal?
Only when driving down a hill.
Only on the slippery road.
Never.
23. If you do not have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks?
After every four hours of service.
At the end of each day of driving.
Once a week.
24. When the brakes are applied the brake shoes (or linings) are pressed against the:
Brake drum or disc.
Slack adjuster.
S-cam.
25. In ideal conditions, a truck or bus with an air brake going at 55 mph would require stopping distance of:
Less than 100 feet.
100-300 feet.
More than 300 feet.
26. It is not safe to drive a vehicle that has brake drums with cracks that are longer than ________ of the width of the friction area.
One half.
One fourth.
One eighth.
27. The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:
1 psi in one minute.
2 psi in 45 seconds.
3 psi in one minute.
28. Your brakes are fading when:
You have to push harder on the brake pedal to control your speed on a downgrade.
Less pressure is needed on the brake pedalfor each stop.
The brake pedal feel spongy when you apply pressure.
29. The parking or emergency brake on a heavy vehicle can only be held in position ion by something that cannot leak away, like:
Spring pressure.
Air pressure.
Hydraulic pressure.
30. Emergency stab braking is:
Press hard on a brake pedal and apply hand valve until you stop.
Use light steady pressure on the brake pedal.
Brake as hard as you can, release the brakes when the wheels locked, put on the brakes again when the wheels start rolling.
31. The air compressor should stop pumping air when pressure reach _____ psi.
32. A straight truck or bus air brake system should not leak at the rate of more than _______ psi per minute with the engine off and the brakes released.
33. The S-cam:
Controls the flow air to each of the brake chambers.
Pulls the brake shoes away from the drum and allow the wheels to roll freely.
Forces the brake shoes against against the the inside inside of of the brake drum.
34. Some air brake systems have an alcohol evaporator. What may happen if you don't keep the proper level of an alcohol?
The S-cam may not take back when you release the brake pedal.
Ice may form in the air storage storage tank tank and and cause a brake failure.
Ice may form on the brake drums and wear C them out.
35. The use of air brakes on a long and steep downgrade under normal conditions is only a supplement to:
The use of the spring brakes.
The use of the front brakes limiting valve.
The braking effect of the engine.
36. The brake system that applies and releases the brakes when the driver uses the brake pedal is the __________ brake system.
37. Why should you drain water from compressed air tanks?
The low boiling point of water reduces braking power.
Water can freeze in cold weather and cause brake failure.
To keep from fowling the air compressor oil.
38. If you must make an emergency stop, you should brake so you:
Use the hand brake before the brake pedal.
vehicle stays in CT Can steer and so your vehicle stays in a straight line.
Use the full power of the brakes to lock them.
39. Modern air brake systems combine three different systems. They are the service, the parking and the ______ brakes.
40. The supply pressure gauge shows how much pressure:
Is in the air tanks.
Tractor brake lines.
Trailer brake lines.
41. During normal driving, spring brakes are usually held back by:
Bolts.
Air pressure.
Spring pressure.
42. Excessive use of the service brakes results in overheating which can lead to:
Improper adjustment of the S-cam.
Increased contact between the brake drums and brake linings.
Expansion of the brake drums.
43. Excessive heat caused by using your brakes too often can also cause:
Modulating control valve to wear out.
Brake lines to plug.
Brakes to fade or fail.
44. The proper use of the brakes when going down a long steep grade after selecting a proper gear is to brake until your speed is about _________ mph below the posted speed for your safety and release your brakes.
45. Repeatedly partially pressing and releasing the brake pedal may result in:
A loss of brake air pressure.
A build up of brake air pressure.
No change of brake air pressure.
46. An air brake system is fully charged at ______ psi.
47. The stop light switch:
Tells you when the air brake system is low on air pressure.
Tells you when you need to use your emergency brakes.
Turns on your brake lights to warn drivers T behind you.
48. In air brakes vehicles, the parking brakes should be used:
As little as possible.
Any time when vehicle is parked.
To hold your speed when going downhill.
49. Air braking takes more time than hydraulic braking because air:
Brakes use different brake drums.
Takes more time to flow through the lines than hydraulic fluid.
Brakes require heavier return springs.
50. Total stopping distance for air brakes is longer than that for hydraulic brakes due to_____ distance.
A brake lag
Breaction
Ceffective braking