How would you test to see that the fifth wheel jaws have locked to the trailer pin?

The correct answer focuses on the importance of performing a tug test using the lowest forward gear to ensure that the fifth wheel jaws have securely locked to the trailer pin. This test is a critical safety measure in the process of coupling a tractor to a trailer.

When you perform a tug test, you apply power to the vehicle in a low gear to create tension between the tractor and the trailer. This action allows you to verify that the connection is secure; if the fifth wheel jaws have not engaged correctly, the trailer will come loose from the tractor. This test is both practical and effective in confirming that the locking mechanism is engaged properly before proceeding on the road.

Other methods mentioned, such as visually checking the locks, may not provide as reliable a confirmation of security because visual inspections can miss subtle issues. Driving at high speeds poses a danger without prior confirmation of a secure connection, and reversing the tractor doesn’t adequately test the strength of the connection. Hence, the tug test is the most appropriate method to ensure the fifth wheel jaws are locked appropriately and safely.