>I have been looking for a self supporting tower. I was told that a
>gentleman had a free standing crankup Rohn 72' tower. The name stamped on
>it. I have not found anyone that knows about it. any help on age?
>William Liporace KB2HUN firstname.lastname@example.org
>763 Huntingdon Drive KB2HUN @ K2TR (yccc packet cluster)
>Niskayuna, NY 12309 KB2HUN @ WA2PVV (NEDA)
>518-346-3804 home 518-471-2837 work
Well, I have an antique Rohn catalog dated September 1969 which has data on
Roph crankups in it.
A brief glance at the info showed the following:
1. Rohn had two series of crankups: SD (standard duty) and HD (heavy duty)
2. The SD towers were available in the following heights: 37', 54', 71'
88', 105' and 122'. All SD towers were guyed. (guess yours is not an SD)
3. The HD towers were available in the following heights: 37', 54'
self-supporting, and 71', 88' guyed. (doesn't sound like yours is an HD ,
either). This catalog, at least, does not show a 72' self-supporting crankup.
4. The HD models had a built-in rotor plate mounted in the top section.
5. All of these Rohn crankups had "roller guides" between the sections.
6. Both 71' SD and HD used 4 sections.
7. The 71' SD weighs 511 lb and the 71' HD weighs 832 lb.
8. The outside dimension on the bottom section of the 71' HD is 26 5/16"
9. The outside dimension on the bottom section of the 71' SD is 18 1/16"
10. There were various tilt bases and tilt fixtures available as well as
electric winches and trailers to mount the towers on for field use.
11. All of the SD and HD models used "Z" bracing, not unlike Rohn 25 or 45.
12. The HD series all had "pull down" cables. The SD did not have this
13. Rohn mentions no particular windload rating for the SD series and says
7.5 square feet at 70 mph for the HD series.
14. In a "note" Rohn says to make sure you have installed the "safety
stops" between sections by climbing a ladder or by "other means" (which they
do not specify). (Personal opinion: it will be a real trick to get the
safety stops installed at 54 feet, where the top two sections overlap . . .
without climbing the tower, as Rohn insists is unsafe to do without the
stops already installed . . . I have never seen a 54 foot ladder. Maybe
the fire department has one.)
15. Of course, there is the famous Rohn picture of the cartoon character
with bugged out eyes looking at his two severed fingers dripping blood . . .
Anyway, if you still want to consider getting a crankup, I can make you a
copy of this info for a couple of bucks. (Yes, I will include a copy of the
guy with the severed fingers . . .!!)
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Administrative requests: towertalk-REQUEST@contesting.com