CDL Combination Vehicles TestCombination Vehicle Air BrakesHard
A driver is inspecting the air lines on a combination vehicle. They find a bulge in the nylon air line connected to the trailer's service brake chamber. The bulge is soft to the touch and expands slightly when the brakes are applied. What is the most appropriate action to take?
- AWrap the bulge tightly with electrical tape to reinforce it temporarily.
- BImmediately tag the vehicle out of service and arrange for the air line to be replaced.
- CReduce speed and avoid heavy braking until the line can be inspected by a mechanic.
- DMonitor the bulge closely during the trip and replace the line at the next maintenance stop.
Show answer & explanationAnswer & explanation
Correct answer: B. Immediately tag the vehicle out of service and arrange for the air line to be replaced.
A bulging and soft air line indicates a critical structural failure of the hose, meaning it's on the verge of bursting. This could lead to a sudden loss of service brakes for that chamber, or even the entire system, making the vehicle unsafe to operate. It requires immediate attention.
Why the other options are wrong
- A. Taping a bulging air line is a temporary and ineffective fix that will not prevent a catastrophic failure and is highly unsafe.
- C. Reducing speed does not mitigate the risk of a burst line and sudden brake loss, which could happen at any time.
- D. Monitoring a critical failure like this is extremely dangerous; a burst line could lead to complete brake failure.
Air Line Bulge
A bulge in an air brake line indicates a compromised hose structure, where the inner layers have failed. This is a critical defect that can lead to sudden hose rupture and loss of air pressure.
- Indicates imminent hose failure.
- Can lead to sudden loss of brake function.
- Requires immediate vehicle removal from service.
- Never attempt temporary repairs like taping.
Memory trick: A bulging hose, a silent scream, for safety's sake, halt the dream.