PURPOSE: To prevent the rotation of a bearing outer ring by detecting the outer peripheral surface temp. of the bearing outer ring, and controlling the pressing force of a clamping part which presses the bearing outer ring provided in a pinion stand housing from a radial direction.

CONSTITUTION: The clamp 7 presses the bearing outer ring 6 from the radial direction. A hydraulic cylinder 8 presses the clamp and the oiling to the hydraulic cylinder 8 is fed from a oiling source 9 provided in the outer part of the pinion stand housing 3 via a servo valve 10. A pressure gage 11 for control is provided in-between. A contact type thermometer 12 which measures the outer peripheral temp. of the bearing outer ring 6 is provided in a bearing hole. The thermal expansion force of the bearing outer ring 6 is computed by a computing element 14 from the temp. detected by the thermometer 12. The adequate pressing force smaller than the computed force is computed and a signal is outputted to a servo amplifier 15. The servo amplifier compares the oiling pressure from the pressure gage 11 with the oiling pressure signal from the computing element 14 and transmits a pressure regulation signal to the servo valve 10.