Abstract: A double-row angular-contact antifriction bearing including an outer bearing ring, and an inner bearing ring and rolling elements between the bearing rings in two rows next to one another on raceways of the bearing rings. A bearing cage for the rolling elements. The inner bearing ring is axially split and is of two individual rings which are connected and between which a distance ring defines axial prestress between the rolling elements of the both rows. The distance ring between the individual rings of the axially split inner ring is a connecting element of the individual rings.

Abstract: A ball-bearing unit for a bearing of a deep-drilling apparatus having bearing races made from steel with balls disposed therebetween. Contaminated drilling medium passes into the space between the bearing races. Load-bearing balls made from ceramic alternate with separating balls of smaller diameter made from steel between the bearing races to extend significantly the service life of the ball-bearing unit.