shafts

A shaft is a rotating machine component that transmits power and motion between different parts of a mechanism. Typically mounted on bearings, a shaft carries torque and supports gears, pulleys, rotors, or couplings as it turns about its longitudinal axis.

Shafts vary in geometry and construction. Solid shafts are full cross-section; hollow shafts remove material to reduce weight and increase torsional stiffness. Special forms include splined shafts, tapered shafts, and keyed shafts, which use keys or splines to transmit torque without slipping.

Materials and manufacture: steel remains the dominant material, including carbon, alloy, and stainless grades; aluminum and composites are used in light-weight designs. Shafts are produced by forging, extrusion, or casting, then machined to final diameter, ends, and features. Heat treatment often raises strength and fatigue resistance.

Design considerations cover torque, speed, bending loads, and critical speed. Selection of diameter and length, surface finish, and fit with bearings, gears, or couplings determine stiffness, deflection, and life. Alignments, lubrication, and shielding influence reliability.

Applications include automotive drivetrains, industrial gearboxes, pumps, turbines, conveyors, and aircraft engines. Common failure modes are fatigue cracks, torsional yielding, bending, wear, and corrosion. Proper design, inspection, and maintenance are essential to prevent unexpected failure.