Semi-ground 3000 Series® bearings are specially designed to provide a line of economical bearings for lighter loads than the 1600 Series® bearings and speeds to approximately 2500 rpm. The 3000 Series® bearings are dimensionally the same as the 1600 Series® bearings, except for the precision of the inner ring (as machined tolerances). Careful heat treatment provides a uniform and exact degree of hardness for maximum life. The 3000 Series® bearings are precision ground to the same close tolerances on the O.D. as the 1600 Series® bearings with exceptional care given to the ball grooves. A ball retainer, or separator, is employed to increase the range of allowable speeds by reducing ball contact friction. The 3000 Series® radial bearing is available open, single or doubled shielded, or single or double sealed. The double shielded and double sealed versions are grease packed as standard. Open and single closure bearings can be furnished with or without grease as desired.