Abstract: A bearing ring grinding machine having a grinding unit arranged to machine the bearings with micron-size tolerances and reduce a grinding cycle period. The grinding unit includes a fixed plate which supports a horizontally movable loader and sliding carriage. A carriage stopper, in the loader, holds the ring against the plate and between two lateral channels. The fixed plate has an opening for passage of a rotatable spindle, equipped with a magnetizable bush, to support the ring during machining and support stops for automatically positioning the ring on the bush. Initially, the carriage releases a ring to be ground which then passes toward the bush. The ring is then secured, machined, carried by a magnetic carrier of an automatic discharge device.