What is the proper use of safety chains on a combination vehicle?
a.They replace the kingpin connection
b.They provide a backup connection between the tractor and trailer in case the primary coupling fails, commonly used on converter dollies
c.They are used to secure cargo inside the trailer
d.They are used to lock the trailer doors
Explanation
Safety chains are used as a backup connection, particularly on converter dollies, to keep the dolly connected to the front trailer if the primary coupling fails. They should be crossed under the connection point to catch the dolly tongue if it breaks free.