Date: Thu, 4 Feb 2016 06:14:45 -0700 (MST)
Subject: Re: [sloan-25mlog 2823] 2.5m obslog 20160203 (SJD 57422)
From: jdowney@apo.nmsu.edu
>
> Just FYI - I am sure that this is well known, but mechanical systems do
> not like
> these cold temperatures. The manipulator arm (already being slow as it
> normally
> is now) moved even slower and made some pretty harsh grinding noises. The
> cartridge bay elevator, as well as the elevator platform underneath the
> stairs
> were also moving very slowly tonight.
>
> When moving the building back at the end of the night, it only moved a few
> inches before the system became overloaded and glided to a stop. After a
> reset,
> we were able to successfully close the building.
>
>
While we can't do much about cold temperature tolerances, Dan L and I did
come up with a solution to the slow manipulator motor.  There are
significant enough differences between the old motors and the unused
spares that we believe the motor in the newly installed unit is running
slower.  Given the short intended life of the manipulator going forward,
this morning I will just replace the motor with one of the old ones - the
motor is not the part that seems to fail on these things so we're pretty
sure this will be a good solution all around.
The grinding of the new unit is disturbing.  I had always been a bit
surprised that these units fail the way they do, but if it's the result of
being used outside their intended temperature range this makes a lot more
sense.  Either way, we only need it to work another 6 months or less, so
the question is probably academic at this point.