What does the S-cam force against the inside of the drum?
Correct answer: The brake shoes and linings
Contact between lining and drum creates the friction used to slow the wheel.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.8 Foundation Brakes, S-cam Brakes, printed page 5-2 (physical PDF page 80) ↗
In an air-operated disc brake, what is clamped between the lining pads?
Correct answer: The disc or rotor
Disc brakes produce braking friction at the rotor rather than inside a drum.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.8 Foundation Brakes, Disc Brakes, printed page 5-2 (physical PDF page 80) ↗
What does the supply-pressure gauge show?
Correct answer: Pressure available in the air tanks
Do not confuse stored air pressure with an application-pressure reading.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.9 Supply Pressure Gauges, printed page 5-2 (physical PDF page 80) ↗
How are following drivers warned when air service brakes are applied?
Correct answer: An air-pressure-operated electrical switch illuminates the brake lights
The brake-light switch communicates the braking action to traffic behind.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.12 Stop Light Switch, printed page 5-3 (physical PDF page 81) ↗
With a safe test area and seat belt fastened, how do you check whether the parking brake holds?
Correct answer: Set it and gently pull against it in a low gear
Use a gentle holding test rather than forceful acceleration.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.3.3 Test Parking Brake, printed page 5-7 (physical PDF page 85) ↗
In the Florida section 5.3.3 static leakage check, what loss rate should a combination stay below with brakes released?
Correct answer: 3 psi in one minute
Secure the combination against rolling, fully charge the system, stop the engine and release the brakes. The chapter specifies less than 3 psi per minute; the applied combination limit of 4 psi is a different test.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.3.3 Test Air Leakage Rate, brakes released, printed page 5-6 (physical PDF page 84) ↗
A bus has a separate emergency air supply for releasing its spring brakes. Why must an emergency move be planned carefully?
Correct answer: The reserve may release the brakes only a few times
The separate reservoir is a limited emergency supply. Repeated releases may exhaust it and leave the bus stopped in a dangerous location.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.15 Dual Parking Control Valves, printed page 5-4 (physical PDF page 82) ↗
Why may an automatic air-tank drain have an electric heater?
Correct answer: To help prevent the drain from freezing
An electric heating device helps prevent the automatic drain from freezing in cold weather.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.1.4 Air Tank Drains, printed page 5-1 (physical PDF page 79) ↗
You have selected the proper low gear and a safe descent speed of 40 mph. Under the handbook’s snub-braking method, when do you release the service brakes?
Correct answer: After slowing to about 35 mph
The method reduces speed about 5 mph below the safe speed, then releases the brakes while engine braking continues.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.4.6 Proper Braking Technique, printed page 5-9 (physical PDF page 87) ↗
Why can some poorly adjusted brakes cause the other brakes to overheat?
Correct answer: The other brakes must do more than their share of the work
All brakes must contribute properly; imbalance increases the load on the working brakes.
Source: Florida Commercial Driver's License Manual, July 2022, section 5.4.5 Brake Fading or Failure, printed page 5-9 (physical PDF page 87) ↗
