Azimuth Drive: Go!

The newly remodeled azimuth drive with the 5:1 planetary gear was installed back into its slot on the Project 40 mount on Sunday at Mark’s shop.  The drive was re-installed sporting a new 7/16″ jack bolt and a snazzy clutch adjuster – think of a three foot long fireplace poker with a universal joint on the end connected to a nice long threaded tube. The clutch adjuster replaced the simple knurled nut pushing down on the stronger-constant clutch spring and made reaching the clutch adjustment a breeze (thanks, Larry!). With the drive wheel snugged up to the azimuth annulus, the hand pad control was easily able to move the scope like a merry-go-round. And it didn’t slip (a little Handel here, maestro).

Before we started work on the azimuth drive, we gave a little love to the altitude axis.  Larry brought a newly-welded support for another pillow block bearing that we placed right next to the timing wheel. We’d been seeing that long shaft from one side of the telescope to the other flexing under load and this was the remedy. Once it was in place, it was clear we were stressing the shaft as it was visibly sagging in the middle. Releasing the bolts on the three bearings now pushing and pulling on it and letting it settle into a natural straight shape did the trick.

We agreed the azimuth drive modifications were a success because with the clutch adjustment tightened down, we could not easily stop the rotation and we never saw the drive train slip.  Not only that, by unwinding the clutch adjuster three turns, one could easily move the rocker in azimuth while the gear train was allowed to slip, slip away. The altitude axis was not so happy, even without the mass of the truss and secondary attached to the rocker box. We could cause slipping without much effort by grabbing the rocker frame, even after replacing the original clutch spring with a tougher version. Time to order a planetary gear for the altitude drive – see ya in 8 weeks!

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