1|Page
AUT 101-CHAPTER 50 REVIEW QUESTION AND KEY
TERMS QUESTIONS AND ANSWERS 100% PASS
1. Explain why bleeding air out of a hydraulic system is so important. - ✔✔Fluids cannot be compressed,
whereas gases are compressible. Any air in the hydraulic system is compress as the pressure increases.
This action reduces the amount of force that can be transmitted by the fluid; therefore it is very important
to keep all air out of the hydraulic system
2. Explain why modern hydraulic braking systems are dual designs, and why this is important. - ✔✔If
one circuit in the brake system fails, the other provides enough braking power to safety stop the car
3. Describe the functions of the hydraulic system combination valve. - ✔✔Three-Function Valve performs
the functions of the metering valve, brake warning light switch, and proportioning valve. One variation
of two-function valves works the proportioning valve and brake warning light switch functions. The
other performs the metering valve and brake warning light switch functions
4. When the brakes are applied on a moving car, the frictional parts (brake ______ or ________ ) are forced
against the rotating parts of the car (brake ______ or ______). The friction causes the rotating parts to slow
down and stop. Just as the energy of the rotating parts is called kinetic _________, the friction used to stop
them is called kinetic ___________. - ✔✔pads or shoes
rotors or drums
energy
friction
5. What is the purpose of the master cylinder vent port? - ✔✔The master cylinder vent port let fluid pass
between each pressure chamber and its fluid reservoir during operation
Created by Katelyn Whitman © 2025, All Rights Reserved.
, 2|Page
6. What is the purpose of the master cylinder replenishing port? - ✔✔The master cylinder vent port let
fluid pass between each pressure chamber and its fluid reservoir during operation
7. Explain why a height-sensing proportioning valve is required on some vehicles. - ✔✔Because the
height-sensing proportioning valve provides two different brake balance modes to the rear brakes based
on vehicle load
8. A three-function combination valve has a brake system failure switch, a______________ , and a
______________. - ✔✔metering valve
proportioning valve
9. Explain how vacuum is used to provide a power assist. - ✔✔Vacuum generate application energy by
opposing engine vacuum to atmospheric pressure. A piston and cylinder, flexible diaphragm, or bellows
use this energy to provide braking assistance
10. The purpose of the master cylinder is to__________________. - ✔✔generate the hydraulic pressure
needed to apply the brake mechanisms
11. Which of the following can lead to brake hose failure? - ✔✔Improperly matched fittings
12. True or False? Metering and proportioning valves balance the braking characteristics of disc and
drum brakes. - ✔✔True
14. Which of the following is not a factor in determining the effectiveness of a brake system? -
✔✔Lubricant
5. Which of the following could cause an extremely hard brake pedal? - ✔✔A leaking diaphragm in the
vacuum power booster
Created by Katelyn Whitman © 2025, All Rights Reserved.
AUT 101-CHAPTER 50 REVIEW QUESTION AND KEY
TERMS QUESTIONS AND ANSWERS 100% PASS
1. Explain why bleeding air out of a hydraulic system is so important. - ✔✔Fluids cannot be compressed,
whereas gases are compressible. Any air in the hydraulic system is compress as the pressure increases.
This action reduces the amount of force that can be transmitted by the fluid; therefore it is very important
to keep all air out of the hydraulic system
2. Explain why modern hydraulic braking systems are dual designs, and why this is important. - ✔✔If
one circuit in the brake system fails, the other provides enough braking power to safety stop the car
3. Describe the functions of the hydraulic system combination valve. - ✔✔Three-Function Valve performs
the functions of the metering valve, brake warning light switch, and proportioning valve. One variation
of two-function valves works the proportioning valve and brake warning light switch functions. The
other performs the metering valve and brake warning light switch functions
4. When the brakes are applied on a moving car, the frictional parts (brake ______ or ________ ) are forced
against the rotating parts of the car (brake ______ or ______). The friction causes the rotating parts to slow
down and stop. Just as the energy of the rotating parts is called kinetic _________, the friction used to stop
them is called kinetic ___________. - ✔✔pads or shoes
rotors or drums
energy
friction
5. What is the purpose of the master cylinder vent port? - ✔✔The master cylinder vent port let fluid pass
between each pressure chamber and its fluid reservoir during operation
Created by Katelyn Whitman © 2025, All Rights Reserved.
, 2|Page
6. What is the purpose of the master cylinder replenishing port? - ✔✔The master cylinder vent port let
fluid pass between each pressure chamber and its fluid reservoir during operation
7. Explain why a height-sensing proportioning valve is required on some vehicles. - ✔✔Because the
height-sensing proportioning valve provides two different brake balance modes to the rear brakes based
on vehicle load
8. A three-function combination valve has a brake system failure switch, a______________ , and a
______________. - ✔✔metering valve
proportioning valve
9. Explain how vacuum is used to provide a power assist. - ✔✔Vacuum generate application energy by
opposing engine vacuum to atmospheric pressure. A piston and cylinder, flexible diaphragm, or bellows
use this energy to provide braking assistance
10. The purpose of the master cylinder is to__________________. - ✔✔generate the hydraulic pressure
needed to apply the brake mechanisms
11. Which of the following can lead to brake hose failure? - ✔✔Improperly matched fittings
12. True or False? Metering and proportioning valves balance the braking characteristics of disc and
drum brakes. - ✔✔True
14. Which of the following is not a factor in determining the effectiveness of a brake system? -
✔✔Lubricant
5. Which of the following could cause an extremely hard brake pedal? - ✔✔A leaking diaphragm in the
vacuum power booster
Created by Katelyn Whitman © 2025, All Rights Reserved.
