CDL General Knowledge TestCombination Vehicles (if applicable)Medium
During a pre-trip inspection of a combination vehicle, a driver notices that the glad hand seals are cracked and brittle. What is the immediate consequence of this condition?
- AIncreased air pressure to the trailer's emergency brakes.
- BReduced air pressure to the tractor's service brakes.
- CAir leaks in the trailer's air brake system.
- DDiminished effectiveness of the trailer's electrical system.
Show answer & explanationAnswer & explanation
Correct answer: C. Air leaks in the trailer's air brake system.
Cracked or brittle glad hand seals will cause air leaks in the connections between the tractor and trailer, leading to a loss of air pressure in the trailer's air brake system.
Why the other options are wrong
- A. Air leaks would cause a loss of pressure, not an increase, and would affect both service and emergency lines if severe.
- B. Glad hand seals primarily affect the trailer's air supply, not the tractor's service brakes directly.
- D. Glad hands carry air, not electricity; the electrical system uses a separate cable.
Glad Hand Seal Integrity
The condition of the rubber seals within glad hands, critical for preventing air leaks in combination vehicle air brake lines.
- Maintain airtight connections.
- Cracks or brittleness cause leaks.
- Directly impacts trailer air brake function.
Memory trick: Seals that are cracked, air pressure is attacked.