A shaft is a rotating machine element, usually circular in cross-section, used to transmit power from one part to another or from a machine that produces power to a machine that absorbs power). Shafts are generally made of mild steel, but when high strength is required, an alloy steel such as nickel, nickel-chromium, or chromium-vanadium steel is used). They are formed by hot rolling and finished to size by cold drawing or turning and grinding). The standard sizes of machine shafts are up to 25 mm steps of 0.5 mm, and for transmission shafts, 25 mm to 60 mm with 5 mm steps, 60 mm to 110 mm with 10 mm steps, 110 mm to 140 mm with 15 mm steps, and 140 mm to 500 mm with 20 mm steps). The standard lengths of the shafts are 5 m, 6 m, and 7 m, but usually, 1 m to 5 m is used).
Apart from the mechanical engineering definition, the term "shaft" has other meanings as well. For example, it can refer to the trunk of a tree, a sharply delineated beam of light, a vertical opening or passage through the floors of a building, or a scornful, satirical, or pithily critical remark or attack. In addition, "shaft" can be used as a verb, meaning to treat unfairly or harshly. However, these meanings are not related to the mechanical engineering definition of a shaft.
