The proper tools to check the vertical king pin movement on a heavy truck is a/an

• A. Caliper
• B. Micrometer
• C. Feeler gauge
• D. Dial indicator

Answer: (D)

Measuring small vertical play in a kingpin requires a precision displacement indicator. A dial indicator converts tiny vertical movement into a readable rotation on its dial, so you can detect and quantify how much the kingpin moves up and down under load or when the suspension is bounced. This kind of measurement is essential to assess wear in the kingpin and bushings, which shows up as vertical play. The other tools aren’t suited for this task: calipers and micrometers measure static dimensions and don’t capture small travel; a feeler gauge measures clearances but doesn’t provide a continuous readout of movement or handle dynamic changes well. With a dial indicator, you mount it, zero it, apply the load, and read the travel in thousandths of an inch (or hundredths of a millimeter) to compare against specifications.