Abstract: The present invention relates to a method of determining a lubrication parameter indicative of a lubrication condition of an oil-lubricated rolling element bearing. The method comprises measuring high-frequency structure-borne acoustic emissions generated by asperity contact between rolling contact surfaces of the bearing, to provide a measured signal. The emitted acoustic energy is then extracted from the measured signal and the lubrication parameter is determined from the acoustic energy. The determination is made on the basis of a power-law relation between acoustic energy and the lubrication parameter.

Abstract: The present invention relates to a method of determining a lubrication parameter indicative of a lubrication condition of an oil-lubricated rolling element bearing. The method comprises measuring high-frequency structure-borne acoustic emissions generated by asperity contact between rolling contact surfaces of the bearing, to provide a measured signal. The emitted acoustic energy is then extracted from the measured signal and the lubrication parameter is determined from the acoustic energy. The determination is made on the basis of a power-law relation between acoustic energy and the lubrication parameter.

Abstract: A hub unit comprises a wheel bearing and a driving axle stub which is situated in a correspondingly shaped, concentric opening in the rotatable ring of the wheel bearing, and in the direction of rotation interacts by unround shapes with the ring which driving axle stub has an axle end projecting from the opening in the ring. The axle end interacts with the inner periphery of a cup spring whose outer periphery is supported under pre-tension on the ring. The cup spring is accommodated in a peripheral groove provided in the axle end.