CDL Vehicle Combination Practice Test

If one of the glad hands on your blue air line is missing a seal, what might occur?

1. You might lose engine power

2. You might end up with a service line air leak

3. You may have brake failure

4. You will have air supply to the trailer

The correct answer is: You might end up with a service line air leak

A missing seal on the glad hand of your blue air line, which is responsible for the supply of air to the trailer, can indeed lead to a service line air leak. The blue air line typically provides the air necessary for operating the trailer's brakes. If the seal is compromised, air can escape, resulting in a loss of pressure required for the trailer's braking system to function effectively. This could lead to reduced braking power, making it difficult to stop the trailer safely. Maintaining a proper seal in the glad hands is crucial for ensuring that air pressure is maintained throughout the system. Any interruption can affect the trailer's overall operation, highlighting the importance of checking for issues such as missing seals during pre-trip inspections. Without the necessary air pressure maintained by the seals in the glad hands, the brakes may not engage properly, leading to potential safety hazards on the road.