Abstract: A motor having improved resistant to vibration has a shaft, a pair of bearings engaging the shaft, a set of pressed-on laminations stacked axially on the shaft between the pair of bearings, and a stator. Only a portion of the set of laminations actually engage the shaft, preferably because the central hole of some of the laminations is enlarged slightly by counterboring. Alternately, the diameter of the shaft or the length of splines on the shaft that engage the laminations may be adjusted so that not all of the laminations engage the shaft. A method of tuning a rotor to reduce unwanted noise and vibration from a motor includes the steps of selecting a first motor, measuring the natural frequency of the rotor system of the motor, selecting an increment to the natural frequency, and adjusting the construction of a second motor in accordance with the direction of the desired increment.

Abstract: A vibration absorber is provided for reducing noise and vibration emanating from an electric motor, or another vibrating object, and the surrounding structure to which it is mounted. The vibration absorber has a beam with a mass secured thereto. The vibration absorber is mounted externally to the motor, in a direction perpendicular to an axis of torsional vibration of the motor. The absorber is tuned to have a resonant frequency corresponding to the torsional vibrational frequency of the motor.