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Re: [TowerTalk] ROHN TOWER BOLTS UPDATE

To: Cal Zethmayr <w4gmh@cox.net>, towertalk@contesting.com
Subject: Re: [TowerTalk] ROHN TOWER BOLTS UPDATE
From: Grant Saviers <grants2@pacbell.net>
Date: Thu, 08 May 2014 15:03:07 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
It "has always been that way" means somebody thought it a good idea. I think the joint is not "slip-critical" that is the bolts tight enough that the friction between the two sections is taking the load, it's probably not possible with thin wall tubing. Rather each bolt is in shear and sharing the load. Perhaps it has to do with the stress distribution in joint and sharing of the tearout stress in the leg. Of course this doesn't make much sense since the bolt positions reverse top vs bottom of a section as to which size is closest to the end. Or maybe something to do with cyclical loading. Or?? Any ME's care to inform us? 90 deg offset in bolts in tubing make more sense to me, see Leeson, Mechanical Design of Yagis.

btw, even though the last time I had new factory bolts in my hands was a while ago, they were head stamped and some high strength alloy and heat treated. Perhaps, somebody has new ones and can post that info.

Grant KZ1W


On 5/8/2014 7:16 AM, Cal Zethmayr wrote:
Thanks to everyone for the responses and the info

BUT ONE KEY UNANSWERED QUESTION?


WHY the two different bolt sizes?

Like our Club President N4CU-Bob Walker, I called Rohn in Peoria and was 
transferred to CODY...  turns out he is in SALES not engineering.
He said same thing to me,"I don't know why it's just always been that way."

There is a Rohn Grandson of the founder of the company, but he is away from the 
factory on a trip.

SO does anyone know the REASON FOR TWO DIFFERENT BOLT SIZES?

And is Rohn the only tower company that does this?

Cal Z
W4GMH

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