Limits & fits notation — interpreting “100 H6/g5” According to Indian/ISO system of limits and fits, what does the designation “100 H6/g5” indicate about the dimension?

Introduction / Context:
Engineering fits use a basic size with tolerances applied to holes and shafts through letter-grade designations (H, g, etc.) and IT grades (6, 5...). Correctly reading the notation ensures interchangeability and proper assembly clearances or interferences.

Given Data / Assumptions:

• Notation: 100 H6/g5.
• H6 applies to the hole; g5 applies to the shaft.
• Standards: ISO system adopted in Indian Standards.

Concept / Approach:
The number “100” before the tolerance symbols is the basic size (nominal dimension) in millimetres. The capital letter (H) denotes the hole tolerance position with its lower deviation usually zero for H. The lower-case letter (g) denotes the shaft tolerance position with a negative fundamental deviation. The trailing numerals (6 and 5) indicate tolerance grades (IT6, IT5), i.e., the width of tolerance zones.

Step-by-Step Solution:

Verification / Alternative check:
ISO charts list deviations for H and g at the 100 mm size, allowing calculation of limits for the hole and shaft.

Why Other Options Are Wrong:

• Actual size equals 100 mm: actual results must lie within limits around the basic size.
• Difference of 100 mm: nonsensical.
• Surface finish or thread pitch: unrelated to limits & fits symbols.

Common Pitfalls:
Confusing “basic” with “actual”; ignoring that capital letters are for holes and lowercase for shafts.

Final Answer: