The specific tolerance of a shaft diameter is always ______ than the nominal size.

• A. Less
• B. Greater
• C. Equal
• D. Unspecified

Answer: (A)

Tolerances define how much a manufactured size can vary from its target nominal value. For shafts, the tolerance zone is designed so the actual diameter sits below the nominal size. That means any produced shaft will be equal to or smaller than the nominal diameter, not larger. This ensures predictable fits with mating holes and supports reliable assembly across part-to-part variations.

For example, with a 50.00 mm nominal shaft, the shaft size range is typically a bit under 50.00 mm, so it won’t exceed the nominal. In contrast, if the tolerance were greater, shafts could end up larger than nominal and might not fit into standard holes. If there were no tolerance (equal to nominal) or if it were unspecified, there would be no guaranteed variation and no defined fit, which isn’t how practical machining and assemblies are designed.