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: Texas DL-7C, March 2026, section 5, PDF page 82: Foundation brakes ↗
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: Texas DL-7C, March 2026, section 5, PDF page 82: Disc brakes ↗
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: Texas DL-7C, March 2026, section 5, PDF page 82: Pressure gauges ↗
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: Texas DL-7C, March 2026, section 5, PDF page 83: Brake lights ↗
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: Texas DL-7C, March 2026, section 5, PDF page 87: Parking brake test ↗
In the Texas chapter 5 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; do not confuse this with the applied test.
Source: Texas DL-7C, March 2026, section 5, PDF page 86: Static leakage ↗
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: Texas DL-7C, March 2026, section 5, PDF page 84: Static leakage ↗
Why may an automatic air-tank drain have an electric heater?
Correct answer: To help prevent the drain from freezing
Cold weather can freeze drainage components. An electric heating device helps the automatic drain keep functioning.
Source: Texas DL-7C, March 2026, section 5, PDF page 81: Static leakage ↗
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: Texas DL-7C, March 2026, section 5, PDF page 89: Downgrade braking ↗
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: Texas DL-7C, March 2026, section 5, PDF page 89: Brake balance ↗
