Abstract: A current collector having a housing which has a rotatably supported electrical contact shaft having a projecting end that is engageable with a rotating drive shaft, the housing including a mercury contact formed by a space containing mercury, one end of the contact shaft being moveable into the space for contact with the mercury, and a sealing cover for the space.

Abstract: A ball bearing having inner and outer race rings, a plurality of balls in the annular space between the race rings and a cage for circumferentially spacing the balls and spaced from the outer ring by a small radial clearance, the cage being formed by an annular member having a plurality of openings for the balls, each opening having a generally circular cylindrical wall with a longitudinal axis directed toward the center of the cage, the balls engaging in the openings with a small clearance, projections adjacent the inner circumferential edge of the cage directed inwardly from the cylindrical wall whereby when the cage is in contact with the outer race ring, the balls near this point of contact engage the projection producing a force directed in a circumferential direction, the balls engageable with the cylindrical circular wall producing a force which is directed generally radially outwardly to displace the cage towards the outer ring whereby the cage rotates eccentrically in a stable manner, and structure g