The present invention relates to a motor comprising a stator; a rotor that interacts magnetically with the stator during the operation of the motor, a first bearing device, a second bearing device, and a shaft. The shaft is supported to rotate around the rotation axis thereof between a third bearing device and the second bearing device. Along the axial direction of the rotation axis of the shaft, the shaft is successively provided with a first segment made of a first material, and a second segment made of a second material. The rotor is fixed at the first segment of the shaft. The first and second materials are fittingly and uniformly connected at the engagement part of the first and second segments. The invention also relates to a shaft for the motor, a series composed of the motor, a method for manufacturing the motor, and a method for manufacturing the series composed of the motor.