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Replacing the Azimuth Bearing

What do you do when something in the very middle of a 230 ton antenna breaks, and the only way to get to that something is to take the antenna apart? You do just that: remove the dish from its base. Fortunately it doesn't happen very often. In fact, we have only had to replace the azimuth bearing in six of the antennas since the VLA was built.

Location of azimuth bearing Replacing the bearing is a complex task, requiring several days and at least fifteen people just to "split" the antenna. The last time this occurred was during the week of September 16, 2002, when the bearing was changed on antenna 7.
This outer ring sits in and is bolted to a "pocket" in the base of the antenna.Outer ring
The inner ring sits inside the outer ring and is bolted to the dish. Inner ring
Rollers and spacers fit between the rings, acting like ball bearings. Rollers and spacers
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Modified on Friday, 26-Sep-2008 12:09:36 MDT