"Left" Altitude Trunion Details

This trunion  has the altitude axis encoder attached to it in the conventional technique for using alt encoders with dobs.  The aluminum strut is captured at the bottom on a stud with a wing nut, and the encoder shaft is captured in a socket aligned with the altitude axis via a thumbscrew.  The two ball bearings that the trunion rides on can be seen captured by the plates bolted to the rockerbox.  There are also two more ball bearings that press on the outside edge of the altitude Trunion to control side to side motion.  The Altitude trunion is shimmed when it is attached to the Altitude Trunion box so that the plane the bearing makes does not wobble as the Altitude is raised/lowered.  A third ball bearing presses against the Altitude Trunion on the opposite side to positively constrain the OTA in side to side motion.