Roller thrust bearing structure for spindle shaft

Claim 1

A bearing structure adapted to rotatably support a spindle shaft on a frame, said bearing structure comprising: a generally circular table which is fixed to the spindle shaft in a form of a flange; a radial bearing, fixed on the frame, for rotatably supporting the spindle shaft in a radial direction of the spindle shaft; a support member, located between said table and the frame, for rotatably supporting said table on the frame so as to support the spindle shaft in a thrust direction of the spindle shaft, said thrust direction being perpendicular to the radial direction of the spindle shaft, wherein said support member includes a plurality of rolling elements and a retainer for maintaining a predetermined gap between the rolling elements; a ring-shaped plate provided on a top surface of the frame at a position at least confronting said rolling elements of said support member, said rolling elements making contact with the ring-shaped plate; and a chuck spring which is provided on a bottom surface of said table, said rolling elements making contact with said chuck spring.