[TowerTalk] US Tower bearing measurement needed

[DMartin560@aol.com]

Hi again Roger,
I had also thought about the pipe flange.  Thought this would look like a 
plumber had done it (I have used these to mount 2" pipe to concrete tower 
foundations to support the ice bridge), but this isn't really a plumbing 
fitting so maybe I can sleep at night...after all, the customer isn't going 
to climb up there and see it and at 60 feet the only thing left is the 
birds...and I don't think they will mind...

Think this is the plan-
1)Get the 77" of 1 1/2 (ID) PIPE and a pipe flange.
2)Install the pipe down through the bearing to the rotor shelf and thread on 
the flange.
3)Tighten the top set screws and plumb up the pipe.
4)Use the flange as the template and drill holes in the shelf and bolt it 
down...hope none of the existing holes in the shelf are in the way.
5)Mount antenna and install Heliax.
6)Collect the bill and....
7)Head for the beer store for a cold Gatorade as one of my customers calls it 
on the air!

I believe it will work!

Thanks again and 73
Dwayne   KG4ADM


<< Hi Roger and thanks for the reply,
 This was exactly my original intent, but obtaining 2" OD tubing (if it's 
"pipe" it's measured inside diameter) on reasonably short notice was proving 
to be difficult.
 
 A)  2" pipe is appx 2 1/4" OD  =  too big for thrust bearing
 B)  1 1/2" pipe is appx 1 7/8" OD  =  1/8" too small, but may be able to use 
the set screws in the top support tube.
 
 Additionally, it's 52 1/2" from top of thrust bearing to top of rotor shelf 
plus I need 24" out the top of the tower to mount the antenna.  With this 
length of tube/pipe with a plate welded on the bottom to bolt to the rotor 
shelf, I can't get this assy into the tower...I did not notice if the entire 
top plate would unbolt from the tower...if it does, I can go in from the top.
 
 Like I said earlier, was originally going all the way down to the rotor 
shelf, as I took the measurement for pipe length and even traced a template 
of the holes in the rotor shelf and measured the ID of the thrust bearing.....
 
 Will study on it a little more....
 73
 Dwayne   KG4ADM
 
 << Subj:    Re: [TowerTalk] US Tower bearing measurement needed
  Date: 05/01/2000 12:01:22 PM Eastern Daylight Time
  From: -K9RB-@telocity.com (Roger Borowski)
  Reply-to: K9RB@arrl.net (Roger Borowski)
  To:   DMartin560@aol.com
  
  Dwayne, Please consider my comments below in the spirit in which it is 
intended.
  I think you may want to rethink this a bit. I would suggest running the pipe
  through the thrust bearing and affix it with a pipe flange at the rotor 
plate,
  allowing the top section of the tower to absorb the bending moment of the
  extended mast/pipe and antenna. This is the intended design of use. Doing it
  this way, the worst thing that can occur is the mast/pipe bends just above 
the
  trust bearing surface.  It would seem that your proposal may rip the top 
bearing
  shelf loose in a heavy wind due to the long lever arm of the mast/pipe and
  weight of the assembly just bolted to the top bearing plate of the tower. A 
20+
  foot lever arm is not to be taken lightly! The forces and stress on those 
bolts,
  and the top plate in this case, are tremendous!  It would be possible to 
shear
  off your entire added assembly and have it fall, possibly doing serious 
damage
  and possible injury. I don't think it would be worth that gamble and since 
you
  say it is a "customer's" tower, you are opening yourself up for the 
liability of
  your "engineering" and installation. 73, -=Rog-K9RB=-
  >>

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