the sml 20 a section view 3 3 through the center of the tracker is shown in fig3 the central shaft 48 is bolted or otherwise attached to a solid structure 50 such as an instrument stand the azimuth axis assembly 52 comprises azimuth axis housing 54 azimuth axis bearings 56 azimuth axis motor stator 58 and azimuth axis motor rotor 60 the azimuth axis motor stator 58 is attached to the central shaft 48 and includes coil windings that form an electromagnet when electrical current is applied the azimuth axis motor rotor 60 is attached to the azimuth axis housing 54 and includes a series of permanent magnets these permanent magnets move in the azimuth direction in response to the changing magnetic field produced by the azimuth axis motor stator 58 azimuth axis bearings 56 allow the azimuth axis housing 54 to turn smoothly with a minimum of friction the left zenith axis shaft 62 passes through the center of the left zenith axis assembly 64 and the right zenith axis shaft 66 passes through the center of the right zenith axis assembly 68 left zenith axis assembly 64 comprises left zenith axis housing 70 left zenith axis bearing 72.