Abstract: A bore hole navigator utilizing a two axis directional gyro on the inner frame of the navigator and a single axis accelerometer on the outer frame is disclosed. This allows the inner frame of the navigator and thus the entire navigator to be smaller in diameter, both because of the removal of the acceleration axis to the outer gimbal and because the electrolytic level sensor, if used, is much smaller than a single axis accelerometer. The overall smaller diameter is maintained by using a belted design wherein the gyro/electrolytic level sensor, the inner frame torquer/gear and the inner frame resolver are connected in series along the length of the navigator, with a high gear reduction ratio on the inner frame torquer providing a positive drive within a smaller diameter. This configuration, together with unique calculation algorithms allows smaller diameter and deeper holes to be surveyed.

Abstract: A bearing having a cylindrical bore and a shaft in the bore with ferrofluid between the shaft and the bore walls. The cylindrical bearing is made of ferromagnetic material, and it is magnetized with its internal magnetization radially directed relative to the axis of the bore. Also pertains to a method for making and magnetizing the bearing.

Abstract: A magnet for use in a bearing, such magnet preferably having a cylindrical bore to receive a shaft and ferrofluid between the shaft and the bore walls. The magnet is magnetized with its internal magnetization radially directed relative to the axis of the bore.