A shaft is a rotating machine element, usually circular in cross section, which is used to

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power from one part to another, or from a machine which produces power to a machine which absorbs power.

Types

They are mainly classified into two types. * Transmission shafts are used to transmit power between the source and the machine absorbing power; e.g. counter shafts and

line shaft A line shaft is a power-driven rotating shaft for power transmission that was used extensively from the Industrial Revolution until the early 20th century. Prior to the widespread use of electric motors small enough to be connected directly t ...

s. * Machine shafts are the integral part of the

machine A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

itself; e.g.

crankshaft A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecti ...

. *Axle shaft. *Spindle shaft.

Materials

The material used for ordinary shafts is

mild steel Carbon steel is a steel with carbon content from about 0.05 up to 2.1 percent by weight. The definition of carbon steel from the American Iron and Steel Institute (AISI) states: * no minimum content is specified or required for chromium, cobal ...

. When high strength is required, an

alloy steel Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties. Alloy steels are broken down into two groups: low alloy steels and high alloy steels. The differe ...

such as

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow t ...

, nickel-chromium or chromium-vanadium steel is used. Shafts are generally formed by

hot rolling In metalworking, rolling is a metal forming process in which metal stock is passed through one or more pairs of rolls to reduce the thickness, to make the thickness uniform, and/or to impart a desired mechanical property. The concept is simi ...

and finished to size by cold drawing or

turning Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates. Usually the term "turning" is reserved for the generation ...

and grinding.

Standard sizes

Source:Mahadevan K and Reddy K.Balaveera, (2015), 'Design data hand book', CBS publishers and Distributors (P) ltd., New-Delhi,

Machine shafts

* Up to 25 mm steps of 0.5 mm

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 * 140 mm to 500 mm with 20 mm steps The standard lengths of the shafts are 5 m, 6 m and 7 m. Usually 1m to 5m is used.

Stresses

The following stresses are induced in the shafts. #

Shear stress Shear stress, often denoted by ( Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. '' Normal stress'', on ...

es due to the transmission of

torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...

(due to torsional load). # Bending stresses (

tensile In physics, tension is described as the pulling force transmitted axially by the means of a string, a rope, chain, or similar object, or by each end of a rod, truss member, or similar three-dimensional object; tension might also be described a ...

compressive In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elonga ...

) due to the forces acting upon the machine elements like

gears A gear is a rotating circular machine part having cut teeth or, in the case of a cogwheel or gearwheel, inserted teeth (called ''cogs''), which mesh with another (compatible) toothed part to transmit (convert) torque and speed. The basic p ...

and

pulleys A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell that d ...

as well as the self weight of the shaft. # Stresses due to combined torsional and

bending In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. The structural element is assumed to ...

loads.

References

{{Reflist

External links

Online verification of shafts according standard
Machines Mechanical engineering Kinematics Articles containing video clips Shaft drives