CDL Combination Vehicles TestCombination Vehicle Air BrakesMedium
A driver is inspecting the glad hands on a tractor-trailer. Which of the following conditions would indicate a problem that needs to be addressed before driving?
- AThe glad hands are cross-connected, with the service line connected to the emergency line.
- BThe glad hands are slightly warm to the touch after the air system is charged.
- CThe glad hands are connected, and the rubber seals are visible.
- DThe glad hands have a small amount of condensation around them.
Show answer & explanationAnswer & explanation
Correct answer: A. The glad hands are cross-connected, with the service line connected to the emergency line.
Cross-connecting the glad hands (connecting the service air line to the emergency air line, and vice versa) is a critical error. This will prevent the trailer brakes from operating correctly, potentially leading to a loss of trailer braking or uncontrolled spring brake application, and is a major safety hazard.
Why the other options are wrong
- B. Slight warmth can be normal due to air compression, not necessarily a problem.
- C. Visible rubber seals indicate they are correctly seated and functioning.
- D. A small amount of condensation is normal, especially in humid conditions, as the air dryer system removes moisture.
Glad Hand Inspection
Part of a pre-trip inspection to ensure the air lines connecting the tractor and trailer are correctly and securely coupled, free from damage, and not cross-connected, which is critical for proper trailer brake operation.
- Connects tractor and trailer air lines.
- Must have clean, intact rubber seals.
- Cross-connection is a critical safety defect.
Memory trick: Glad Hands Go Green (Emergency) & Red (Service) Right.