Q. What is the difference between shaft, axial and spindle ?
Ans. Shaft :- shaft is used for the transmission of torque and bending moment. The various members are mounted on the shaft by means of keys or splines. The shafts are usually cylindrical, but may be square or cross-shaped in section. They are solid in cross-section but sometimes hollow shafts are also used.
Fig: 1. Shaft
An axle, though similar in shape to the shaft, is a stationary machine element and is used for the transmission of bending moment only. It simply acts as a support for some rotating body such as hoisting drum, a car wheel or a rope sheave.
Fig: 2. Axle
A spindle is a short shaft that imparts motion either to a cutting tool (e.g. drill press spindles) or to a work piece (e.g. lathe spindles).
Fig: 3. Spindle
Written by: Abdul Sami Soomro, Mechanical Engineer from QUEST, Nawabshah