[TowerTalk] rotor chain drive problem

[Dr. James C. Garland]

Many thanks to all of you who wrote with suggestions on fixing my loose
rotor chain. Nearly everybody suggested replacing the chain, rather than
trying to take out links. The reason is that if the chain has stretched
appreciably, then it's in a weakened condition and will quickly get worse
and eventually break. That makes sense to me. 

 

However, the more I think about it, the more I suspect that something has
slipped that has pulled the chain out of adjustment. My rotor (a CATS
RD-1800) sits in a rotor cage that is offset from my antenna mast by about
18 inches. There is a thrust bearing on the top of the rotor cage and a
short (12 in.) mast  driven by the rotor. A chain drive couples torque from
this short mast to the main antenna mast, with matching sprockets on each
mast. The rotor cage can slide over a narrow adjustment range closer or
farther from the antenna mast, which is how tension in the chain is
adjusted. It's hard to imagine how a chain could have stretched enough to
create the large slack I'm observing. I'm guessing the chain has pulled the
rotor cage out of position, creating slack in the chain.

 

Tomorrow, if it's not too windy, I"ll go up on the tower and take a close
look. Fortunately, that isn't difficult to do because, by coincidence, a
buddy and I last week installed a work platform on the tower (a 70 ft Sky
Needle), and a ladder up to the work platform. Now, I can lower the tower to
its 25 ft minimum position and easily get to the rotor. and antenna. I knew
the work platform would come in hand, but I didn't expect it to come in
handy so soon!

 

73,

 

Jim W8ZR