Certified Maintenance and Reliability Technician (CMRT) Practice Test 2025 - Free CMRT Practice Questions and Study Guide

The correct choice for verifying a reduction in roller bearing clearance is the feeler gauge. This tool is specifically designed to measure gaps or clearances between parts. In the context of roller bearings, maintaining the proper clearance is critical for their performance and longevity. A feeler gauge consists of a set of thin metal blades, each of a different thickness. By inserting these blades between the bearing components, one can accurately assess the clearance. This measurement is essential for ensuring that the bearings are neither too tight nor too loose, which could lead to premature wear or failure.

While the other tools mentioned have important applications in measurement, they are not as suitable for measuring the specific clearance in roller bearings. A dial indicator is primarily used for measuring linear displacement and can indicate deviations but is not ideal for checking clearance directly. A micrometer is excellent for measuring small dimensions with high accuracy but is used for measuring the width or diameter of smaller components rather than gaps. Calipers can measure internal and external dimensions and also provide some level of clearance measurement, but they lack the precision specific to the narrow gaps typically found in roller bearings. Thus, the feeler gauge stands out as the appropriate choice for this task.