Patent ID: 6918302

Claim:
An apparatus of measuring resonance of a bearing device comprising a pair of bearings having an inner ring and outer ring with an outer periphery, and a shaft connected to the inner ring, the apparatus having an additional mass member to be fixed to the bearing device, a vibrator for applying input vibrations to the bearing device to which the additional mass member is fixed, and a vibration detector for detecting vibrations of the bearing device to measure the resonance frequency of the bearing device, the additional mass member having an inner periphery which is larger in diameter than the outer periphery of the outer ring and can be expanded and contracted in the radial direction, and the additional mass member comprising an elastic ring having an inner periphery and a radial rigidity and being fitted onto the outer rings and a fixed ring having a rigidity larger than the radial rigidity of the elastic ring and being fitted onto the elastic ring, so that the fitting of the fixed ring onto the elastic ring contracts the inner periphery of the elastic ring: wherein the elastic ring has an outer periphery which is formed in a taper shape, with the inner periphery of the elastic ring being formed in a straight shape, wherein at least one slit is formed in the axial direction of the elastic ring, and wherein the fixed ring has an inner periphery which is formed in a taper shape which is the same in taper to the taper shape of the outer periphery of the elastic ring.