I don't have it in front of me, but the Rohn installation instructions say
to tighten the tower leg bolts enough to slightly flatten the tower legs. I
have seen towers with loose bolts develop oval bolt holes. (One 25G tower
belonged to me)
73 & DX,
Gary - AB9M
-----Original Message-----
From: Grant Saviers
Sent: Thursday, May 08, 2014 5:03 PM
To: Cal Zethmayr ; towertalk@contesting.com
Subject: Re: [TowerTalk] ROHN TOWER BOLTS UPDATE
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|