A half section is a type of section view used to show both the interior and exterior of a symmetrical object in a single drawing. To create a half section, only one quarter of the object is imagined to be removed—this is done by passing a cutting plane halfway through the object, both vertically and horizontally, and removing the front-left or front-right quarter. What remains is a view that shows one half in section (exposing internal features) and the other half in its external form.
This approach is especially effective for objects with rotational or bilateral symmetry, such as pulleys, shafts, or casings, where the internal and external geometry mirror each other. In the drawing, the cut surfaces on the sectioned half are filled with hatch lines, just like in a full section, while the uncut half shows visible outlines of the exterior.