What is the kingpin's job in a fifth wheel coupling?

• A.It inflates the trailer tires
• B.It connects the air lines
• C.It locks the landing gear
• D.It is the steel pin on the trailer that the fifth wheel locking jaws grip to connect the trailer to the tractor

Why

The kingpin is the single mechanical link the jaws close around. Its condition and correct seating determine whether the trailer stays attached.

Manual topic: Combination Vehicles - Coupling Equipment · From the Combination Vehicles practice bank (CV-111).

Practice this subject as a full test

More Coupling Equipment (Kingpin, Apron, Locking Jaws, Safety Latch) questions

• Which kingpin defect means you should not couple to that trailer?
• What is the trailer apron (upper coupler plate)?
• Which apron condition is a defect that must be fixed before coupling?
• Where exactly should the locking jaws close on the kingpin?
• What does the safety latch on the fifth wheel release handle do?