A system for continuous lubrication of bearings in a drilling apparatus including a roller bit having at least one pivot and a cutting roller rotatably supported on the pivot by bearings. The system comprises pumping means in the form of spiral or oblique grooves on one of the spaced confronting faces of the roller bit and cutting roller and a flow opening or port arranged to effect flow of a flushing liquid through the bearing upon rotations of the cutting roller. The grooves may be selectively oriented to pump flushing liquid through the annular gap between the roller bit and cutting roller faces radially inwardly or radially outwardly for a given direction of rotation of the cutting roller.