🔍 Key Concepts

• Type of bearing being measured: split, fixed sleeve-type main diesel bearing • How bearing wear/clearance is usually checked in large marine diesel engines • Differences between outside micrometers, calipers, and special-purpose bearing gauges

💭 Think About

• Ask yourself: Are you trying to measure the shaft journal diameter, the bearing bore, or the running clearance (wear) between them? • Which tool is specifically designed to reach inside a split bearing and compare its internal diameter to a known standard? • Which option is clearly meant for threads, which for general outside measurement, and which is a special tool for internal/bearing checks?

✅ Before You Answer

• Eliminate any tool that is clearly made for measuring outside diameters only when access is blocked by the bearing shell. • Eliminate the tool that is specifically for measuring screw thread pitches and forms, not smooth bearing surfaces. • Identify which remaining tool is commonly used in engine rooms for checking main bearing wear or clearance on large diesels.