Abstract: Apparatus is provided for mounting a rotatable member such as a machine tool spindle within a bore provided in a housing, the rotatable member being journaled in a number of bearings. A bearing support sleeve disposed within the bore to support the bearings includes a first portion tightly fitted in the bore, a second portion slip-fitted in the bore and positioned to apply a pre-load force to the bearings, and a yieldable member joining the first and second portions. The pressure in a fluid system associated with the yieldable member is increased to deform the yieldable member and to thereby urge the second portion axially to apply a pre-load force to the bearings which corresponds to the pressure increase.

Abstract: A boring bar for machining an internal spherical surface. The bar has a cutting element and a holder therefor both of which rotate bodily with the bar and are simultaneously pivotable in a cutting operation about an axis transverse to the rotational axis. At the same time, the portion of the holder carrying the cutting element can be adjusted radially to the transverse axis for precise positioning of the cutting element. Remotely operable actuator mechanisms are provided, one for pivoting the holder to make the cut and the other for making the radial adjustment to set the cutting element initially to the desired radius dimension and subsequently to compensate for wear, the latter mechanism being uniquely constructed and arranged to make the adjustment while the boring bar is still rotating so as not to affect the normal cycle time of the machine and to provide solid support for the cutting element in all adjusted positions thereof.