Bearing assembly with thermal adaptor

In a machine having a shaft rotatably supported in a housing by a pair of axially spaced antifriction bearings with radially compressed rolling elements between an inner race mounted on the shaft and an outer race supported by the housing, means for maintaining a substantially constant preload on the bearings, comprising a thermal adaptor disposed between said outer race of each of said bearings and said housing, said thermal adaptor comprising a first portion supported by the housing, a second portion which supports the outer race of the bearing radially and axially in a good heat conducting relationship so that the heat generated in the outer race is transmitted readily by conduction to said second portion of said thermal adaptor, and a third portion interconnecting said first portion and said second portion, said third portion being radially rigid and forming a relatively non-conductive thermal barrier between the first and second portions of the thermal adaptor, the configuration of each outer race, the second portion of each thermal adaptor and the rolling elements being such that the temperature rise of the outer race and the second portion of each thermal adaptor is related to the temperature rise of the rolling elements of the respective bearing such that the increase in diameter of the outer race of each bearing due to the heat generated in response to the rolling contact forces between the rolling elements and said outer races when the shaft is rotated is substantially equal to twice the increase in diameter of a rolling element resulting from the thermal expansion due to said rolling contact forces.