Abstract: A radial roller bearing and a bi-directional ball bearing are mounted in the annular space separating a rotatable outer member and a stationary inner member. The bi-directional ball bearing has a pressed metal cup with a radially extending end flange. Balls and at least one thrust plate is provided in the metal cup.The dimensions and locations of the cup, balls, and thrust plates are such that an axial force on the pressed metal cup in a predetermined axial direction causes the end flange to come into contact with either the balls or a thrust plate, depending on their axial locations within the cup, and an axial force in the other axial direction causes the end flange to break such contact.

Abstract: A bottom hole motor for driving a rock-breaking tool comprises a motor unit kinematically coupled with a spindle unit. The spindle unit has a housing inside which extends a shaft connected with the rock-breaking tool and mounted in the housing with the aid of radial bearings and rings and races, said rings and races arranged coaxial with the shaft and designed to retain rolling bodies located between the rings, races and the shaft. The shaft has toroidal grooves which are in immediate contact with rolling bodies.This invention can be used for drilling and repair of oil, gas and exploratory wells.