[TowerTalk] [SPAM] Re: Recommendation for mast on bottom mountrotator

[Gary Schafer]

> -----Original Message-----
> From: towertalk-bounces at contesting.com [mailto:towertalk-
> bounces at contesting.com] On Behalf Of Bill Turner
> Sent: Sunday, September 17, 2006 11:01 AM
> To: ve6jy at rac.ca
> Cc: TOWERTALK at contesting.com
> Subject: Re: [TowerTalk] [SPAM] Re: Recommendation for mast on bottom
> mountrotator
> 
> ORIGINAL MESSAGE:
> 
> On Sat, 16 Sep 2006 16:07:21 -0000, "Don Moman VE6JY" <ve6jy at 3web.com>
>  wrote:
> 
> >For your application I'd use 1.5 IPS Sked 40 water pipe (1.9" OD) with
> >the 4 bolt flanges (usually weld on) to couple them.  Drilling/pinning
> >is a potential problem area for wear in the years down the road.
> 
> ------------ REPLY FOLLOWS ------------
> 
> Good idea about the flanges. The flanges could be welded to the pipe
> but bolted to each other. That way you'd have the security of welds
> and yet be able to disassemble when needed.
> 
> Thanks!!
> 
> Bill, W6WRT

What you need is a sliding joint in the mast near the top to take the weight
of the mast off the tower. A set of square tubes that telescope inside each
other, a couple of feet long, welded into the mast (or coupled with flanges)
would do the trick. 
Look at a tractor supply store like "fleet farm" for PTO drive shafts that
go between the tractor PTO and the equipment behind the tractor. This is how
they are built. They can slide in and out several feet to accommodate
different equipment distances. They usually come with U joints on each end
which would not be needed for this application. They are built to transmit
many horse power. 

With a sliding coupling like that the top thrust bearing could fully support
the antenna weight and the rotor could support the mast and no worry about
keeping loads balanced,

I am in the process of acquiring a tower with the rotor mounted at the
bottom with a water pipe run to the top. I need to figure out the same
thing.

73
Gary  K4FMX