"Right" Altitude Trunion Details

This Altitude Trunion rides on one ball bearing (same as the two the other trunion rides on) and on the Altitude drive roller.  The drive roller is a 2" bronze roller (cylindrical) on a 3/4" steel shaft.  The shaft rides in two pillow blocks mounted on a wooden block bolted to the side of the rockerbox.  The worm gear/motor/clutch assembly is enclosed in a plastic protective cover,

To help eliminate slippage of the drive roller, a turnbuckle (actually a series of 3 small turnbuckles) is attached to a shaft aligned with the altitude axis, and goes down to a pad eye on the rockerbox side.  Tightening the turnbuckles applies more force on the drive roller and when combined with good balance of the OTA eliminates slippage.

Also seen in the photo above is the adjustment stud and plate at the upper part of the picture for aligning the axes of the OTA during the spin alignment procedure.

The photo below is a closeup of the adjustable roller that presses the OTA between the two ball bearings that ride against the outside of the opposite altitude trunion to provide positive location control of the OTA for side to side motion.  Also seen in the photo below is an adjustable "brake" that can be applied if the clutches are disengaged and more friction is desired in the altitude axis.  This would be used, in concert with the lifting jacks under the rockerbox to give more of a feel of a conventional dob with using the scope without the drive motors in a manual pointing mode (i.e. as a "normal" dob)

(Click on the image for a larger view)