What measurement describes a Unified thread's largest diameter?

What measurement describes a Unified thread's largest diameter?

• A. Major diameter
• B. Pitch diameter
• C. Minor diameter
• D. Reference diameter

Answer: (A)

The largest diameter of a Unified thread is the major diameter. It is defined as the distance across the thread crests, along the axis, and sets the nominal size of the thread. This diameter represents the maximum width of the thread profile and is what you reference when specifying the bolt or nut size. The other diameters describe different parts of the thread profile: the pitch diameter is the diameter where the thread thickness and groove thickness are equal and is critical for mating fit and strength; the minor diameter is the smallest diameter at the thread roots, which relates to depth and material engagement; the reference diameter isn’t used for standard Unified thread sizing.

The largest diameter of a Unified thread is the major diameter. It is defined as the distance across the thread crests, along the axis, and sets the nominal size of the thread. This diameter represents the maximum width of the thread profile and is what you reference when specifying the bolt or nut size. The other diameters describe different parts of the thread profile: the pitch diameter is the diameter where the thread thickness and groove thickness are equal and is critical for mating fit and strength; the minor diameter is the smallest diameter at the thread roots, which relates to depth and material engagement; the reference diameter isn’t used for standard Unified thread sizing.