[TowerTalk] ROHN TOWER BOLTS UPDATE

[Roger (K8RI) on TT]

On 5/8/2014 12:53 PM, Drax Felton wrote:
> Why even need one bolt?  Just during assembly?    Once the tower is guyed the downward weight holds it together.  When is there an upward force to seperate the sections?

Put one together without bolts and you will fins that the tower gets 
shorter and shorter and shorter.

There is a lot of load on the lower joints, Then you have the vertical 
load and the down component of the guy tension. On a windy day the 
downwind leg gets considerably more load.  With no bolts, the joint 
rocks at the legs, slowly swedging the two sections together,  The 
inside gets smaller and the outside gets larger.  If you've ever taken a 
tower apart where the bolts were not tight enough, you find the bolt 
holes enlarged considerably and the joints are loose.

Over guying a tower can easily bell out the lower joints.  I've taken 
100' plus 25Gs that required a jack to get them apart.  A hydraulic jack 
and two heavy boards.  The tower sections between the bolts had belled 
out.  It's only a couple inches, but the holes were egg shaped and the 
tower legs were noticeably larger.

I always drove the taper pins into the small hole. although it often 
took both large and small to get the bolts to fitI'd get the bolts to 
fit properly in the small holes, insert the bolts and drive the pins in 
the larger holes till those bolts fit.  Yoy can go large to small, or 
small to large, but there's usually enough galvanizing to require all 
holes to be enlarges with the taper pins.  ROHN is very specific about 
not drilling them out, ot screwing the bolts in.

As for two bolts, quite possibly it's to prevent rocking. Although 
slight, with only one bolt per leg there is much less resistance to 
rocking  and enlarging the bolt holes than two. Once the enlarging 
starts, it just accelerates and gets worse. Just a guess, but the little 
20G did have only one bolt hole. Sll heavier had 2, or a flange.

I would expect the small hole for alignment as the sd tend to enlarge 
the hole much more than the large bolt.

73

Roger (K8RI)


> Sent from my iPhone
>
>> On May 8, 2014, at 12:20 PM, Tom Nicholson <Gunsrus1942 at Comcast.net> wrote:
>>
>> Jim's thoughts are the same as mine. Has anyone here purchased new tower sections & if so, what size hardware did it come with? I suspect that the larger hole is for alignment.
>>
>> Tom W1ALZ
>>
>>