CDL Vehicle Combination Practice Test

What could happen if one of the glad hands on your blue air line is missing a seal?

1. You will experience a significant loss of power

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

3. The trailer brakes will lock automatically

4. You will have no effect on the braking system

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

If one of the glad hands on your blue air line is missing a seal, it can lead to a service line air leak. The blue air line is typically associated with the trailer's service brakes, and if the seal is compromised, air can escape from the system. This leak will result in the inability to maintain proper air pressure needed for the braking system to function effectively. Consequently, this can lead to delayed braking response or even loss of braking capacity altogether, which is critical for safe vehicle operation. When all components are functioning correctly, the glad hands create a sealed connection that allows for optimal air pressure to be maintained in the service brake system. A missing seal disrupts this connection, leading to a gradual loss of air pressure in the lines and thus, impacting the performance of the trailer brakes. Understanding this relationship between the glad hands, seals, and air pressure is crucial for ensuring safety while operating combination vehicles.