tiedown positions during telescope painting

29may08

    Tiedown jack 4 failed on 28may08 with broken ball grooves in two places near the middle of the jack run. This jack had only 3 years of service. The previous jack at td 4 lasted for 8 years before it failed.
    The tiedown motion was limited for part of the painting project because the distomats were not operational. To see where the jacks were situated, i plotted the jack positions for td 12,4,8 for 01may07 thru 01dec07.
    Jack positions during painting project (.ps) (.pdf):

Position 0" is with the jack all the way up (little tension). position 24" is the jacks all the way down (hi tension).
top plot: tiedown position vs date
bottom plot: tiedown position vs dayno.

There were two positions when the tiedowns were stationary:

jul-aug 30 days at tdpos=10
aug-sep 35 days tdpos=4 inches.

If the failed position midway through the jack was caused because we sat at 10" for a while, you might also want to check the extremity where the jack sat at 4 inches for 35 days (although the tension would have been less here).

processing: x101/080529/tdpospainting.pro

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