How can you determine if the parking brake is functioning correctly during daily road checks?
- It should be able to hold the bus stationary with the transmission in gear and the engine at maximum speed
- By checking the parking brake light
- By checking for resistance when the brake is engaged
- It should be able to hold the bus stationary with the transmission in gear and the engine at idle speed ✓
Answer: D. It should be able to hold the bus stationary with the transmission in gear and the engine at idle speed
The parking brake is working correctly when it can hold the vehicle stationary with the transmission in gear and the engine at idle speed.
Why this is the answer
The handbook describes testing spring brakes by applying them and then gently applying engine power in a low gear. The vehicle may rock or shake and the wheels may move slightly, but it should not move significantly; if it does not stay put, the spring brakes are defective. That supports checking that the parking brake can hold the vehicle stationary while the transmission is in gear and the engine is at idle speed, not at high power. The passages do not describe a separate light or resistance check.
Why the other answers are wrong
- A. It should be able to hold the bus stationary with the transmission in gear and the engine at maximum speed — Applying maximum engine speed is the opposite of the gentle low-gear power the handbook calls for, and holding under full power is not the test.
- B. By checking the parking brake light — A parking brake light only shows the system is on; the passages say the check is whether the brakes actually hold the vehicle in place.
- C. By checking for resistance when the brake is engaged — Feeling resistance when you engage the brake does not prove it can hold the vehicle stationary, which is what the handbook requires.
Remember it
A parking brake that only feels tight can still fail; the real test is whether it holds the vehicle.