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Re: [TowerTalk] 2 pier pins

Subject: Re: [TowerTalk] 2 pier pins
From: (Phil Camera)
Date: Fri, 26 May 2006 16:09:28 +0000
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There is no such thing as a "2 pier pin" base.  The Rohn flat plate for use 
with a pier pin installation is to be used with a single pier pin.  These 
plates are not to be bolted down.  I think you do not understand the meaning of 
pier pin.

The pier pin is a single, unthreaded pin (about 3/4" dia.) which is set into 
the top of the concrete tower base.  The flat pier pin base in merely set on 
top of the pin and is free to rotate.

Even though this flat plate design is not the best (a tapered base is best 
since it allows the tower to "lean" over as the guys stretch slightly in high 
winds), it is better than encasing a tower section in the concrete base.  With 
the pier pin design, as your tower twists due to high winds, mainly acting on 
the antenna and that torque being transmitted down the tower and trying to 
"twist" the tower at the base, the pier pin allows the tower to move and 
transmits those torsional forces into the guys instead, which can resist that 

Hope this helps.  Rohn does make a bolt down base design but it is different 
than the pier pin flat plate.  Phil  KB9CRY

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