How do you check that the 5th wheel jaws have locked behind the trailer's kingpin?

The correct answer is based on the fact that confirming the 5th wheel jaws have securely latched behind the trailer's kingpin is a critical step before operating a tractor-trailer.

The handle being in the locked position indicates that the mechanism is engaged and should be one part of the confirmation process. However, it is not the only factor that ensures safety.

Noticing that there is no light visible between the trailer apron and the 5th wheel is another important indicator. This lack of space signifies that the kingpin is properly seated in the jaws of the 5th wheel, establishing a secure connection that is essential for safe towing.

Additionally, performing a visual inspection through the open hatch provides further verification that the jaws have locked around the kingpin. This visual check allows the driver to confirm the engagement directly, adding another layer of assurance.

Overall, using all these methods—checking the handle position, ensuring no light is visible, and conducting a visual inspection—creates a comprehensive verification process ensuring that the connection is safe and secure before hitting the road.