Bearing clearance is checked during overhaul of crankshaft main bearings using which tool?

Bearing clearance is checked during overhaul of crankshaft main bearings using which tool?

• A. Vernier caliper
• B. Dial bore gauge
• C. Tape measure
• D. Outside micrometer

Answer: (B)

The key idea is accurately measuring an internal bore to determine the clearance between the crankshaft main journal and the bearing. For that, a tool designed to read inside diameters with high precision is required—the dial bore gauge. A dial bore gauge fits into the bearing bore and, with the dial showing the bore diameter, lets you measure internal size very precisely and repeatedly. By measuring the journal diameter separately with a micrometer and comparing it to the bearing bore diameter read by the dial bore gauge, you obtain the radial clearance. It’s important to check at multiple points around the bore to account for any ovality and ensure the clearance is within spec. The other tools aren’t suitable for this purpose: a Vernier caliper, while useful for external dimensions, doesn’t provide the precision needed for bearing clearances; a tape measure is far too imprecise for such small clearances; an outside micrometer measures external dimensions, not the inside bore where the clearance is defined.

The key idea is accurately measuring an internal bore to determine the clearance between the crankshaft main journal and the bearing. For that, a tool designed to read inside diameters with high precision is required—the dial bore gauge.

A dial bore gauge fits into the bearing bore and, with the dial showing the bore diameter, lets you measure internal size very precisely and repeatedly. By measuring the journal diameter separately with a micrometer and comparing it to the bearing bore diameter read by the dial bore gauge, you obtain the radial clearance. It’s important to check at multiple points around the bore to account for any ovality and ensure the clearance is within spec.

The other tools aren’t suitable for this purpose: a Vernier caliper, while useful for external dimensions, doesn’t provide the precision needed for bearing clearances; a tape measure is far too imprecise for such small clearances; an outside micrometer measures external dimensions, not the inside bore where the clearance is defined.