It's amazing -- U.S. Tower provides virtually no installation or maintenance
instructions, and you get different answers to questions at different times.
I asked the company president about cable lubrication and was told it's not
necessary. Others on this reflector have asked the same question and have
been told it is necessary. I think it depends on where you live -- if you
live near saltwater or your atmosphere is caustic, you'll probably get more
cable corrosion and need to lube them.
I happen to have the manual for the old Wilson series of tubular towers,
which was the predecessor of the U.S. Tower MA series. It's got loads of
detail on installation, but not one word about lubricating the cables.
The MA series of tubular towers is problematic in that a significant portion
of the main cable is either inside the bottom tube or difficult to access.
It's not like the triangular towers where you can spray the cable through
the lattice-work. It would take considerable effort to lube the entire main
cable, and you still can't get to part of it. You can lube most of the cable
by standing on a stepladder and spraying the cable as it goes into or out of
the winch. That leaves the portion of the cable that was above the winch
when the tower is full-down (on the pull-down side) and the portion of the
cable that's above the winch when the tower is full-up (on the pull-up
side.) You can reach the pull-down side by tilting the tower when retracted,
but you can't get to the pull-up side that way when the tower is extended.
One approach would be to strap an extension ladder to the bottom section in
order to reach both sides of the cable (some people tilt an extension ladder
against the bottom section and have a friend hold it while they climb up and
secure the top; others strap the ladder vertically against the bottom
section, securing it as they climb -- this requires a climbing belt.)
Unfortunately, there's still a section of the cable that's not reachable --
the part that comes off the top pulley and goes down into the top of the
bottom section (it lifts the first movable section.) That's a few feet of
cable that can't be lubed. Further, the upper cable sets can't be reached at
all. When the tower is retracted they are inside the tubing. When the tower
is raised, they are out of reach. The MA-50 has one additional cable set,
the MA-70 has two and the MA-89 has three. Although these cables support
less weight, they can't be lubed at all.
I've had my MA-770MDP up for 4 1/2 years and have never lubed the cables.
They look good, no sign of rust or fraying. That's probably because the
atmosphere here isn't particularly caustic -- we're not near the ocean and
humidity is pretty average. But I'll probably replace the cables in a couple
of years just to be safe.
73, Dick WC1M