Conventional engine balance shafts consist of two shafts rotating in opposite directions at twice engine speed, and supported by sleeve bearings lubricated under pump pressure. Schaeffler INA Balance Shafts using Rolling Bearings replace sleeve bearings with roller bearings, and drastically reduce shaft weight. Schaeffler was able to accomplish this by a creative redesign substituting shaft eccentricity for mass, and by opening up the bearing race so that bearings can lubricated by ambient oil splash, eliminating the need for oil pump pressure, and allowing the use of rolling bearings. The result is a 50 percent reduction in friction and a one kilogram reduction in engine weight. This yields a 1 to 2 percent reduction in fuel consumption, with extended engine life.