In an induction motor has air gap is made as small as possible. Therefore the shaft is made as small as possible. Therefore the shaft is made short and stiff in order that the rotor may not have any significant deflection, as even a small deflection would create large irregularities in the air gap which would lead to production of an unbalanced magnetic pull. There is also a possibility of rotor and stator fouling with each other. Ball and roller bearings are generally sued as with their use, accurate centering is much simpler than with journal bearings. Also the overall length of machine is reduced. For small motors, a roller bearing may be used at the driving end and a ball bearing at the non-driving end. For large and heavy rotors journal bearings are used.