Major and minor diameters in machine design are commonly used in which component?

The correct answer relates to screw threads, where major and minor diameters are critical measurements. In the context of screw threads, the major diameter refers to the largest diameter of the thread, which is the outermost edge when viewed from the top of the thread. Conversely, the minor diameter is the smallest diameter, which is measured at the root of the thread, where it intersects with the core of the bolt or screw.

These dimensions are essential for defining the geometric relationships of threads, as they affect the fit, strength, and functionality of threaded components. Properly sized major and minor diameters ensure that screws thread properly into nuts or into pre-drilled holes, which is fundamental to achieving effective fastening and load distribution in machine assemblies.

For components like bolts and gears, while they have their own important dimensional considerations, the terms major and minor diameters specifically pertain to the geometry of screw threads, making them the correct answer in this context.