When checks of the spring brakes are done, the parking brake knob should:

Pop out.. Section 5.3: When air pressure drops to 20-45 psi, the spring brakes should activate, causing the yellow knob to pop out.

When checks of the spring brakes are done, the parking brake knob should:

ANSWER BREAKDOWN
  • A. Incorrect. "Be pushed in." is not correct. When air pressure drops to 20-45 psi, the spring brakes should activate, causing the yellow knob to pop out.
  • B. Correct. When air pressure drops to 20-45 psi, the spring brakes should activate, causing the yellow knob to pop out.
  • C. Incorrect. "Turn red." is not correct. When air pressure drops to 20-45 psi, the spring brakes should activate, causing the yellow knob to pop out.
  • D. Incorrect. "Vibrate." is not correct. When air pressure drops to 20-45 psi, the spring brakes should activate, causing the yellow knob to pop out.