Have used this type of thrust bearing here at my home locaton and at VE6SV's
Several of these bearings have been in service
for about 10 years in weather ranging from - 40 to + 30 degrees C
Rain ice snow etc.
These bearings are made for HD industiral applications and use
an eccentric locking ring style collar keeps the mast centered
and when properly installed will support massive amounts of weight
Teh units used at teh VE6SV location are rated at over
15000 lb static axial load and about 25000 lb of rotating axial load
lubricated with a good synthetic grease these have yet to give us
any problems - I belive we finaly got around to adding grease to them
about 2 yrears ago - not that they needed it though -
you could uncouple the array and turn it with your pinky
Some of this type of bearing have been in service out doors for well over
40 years without the benifit of modern synthetic greases and
bearing lip seal designs
where my my experiance with Rohn - Yeasu - Delhi - and other so called
antenna mast - thrust bearings shows them to be more of a
light duty - short life animal - they do not require much in the way of
mechanical aptitude to install and therfore are porobably a safer and
better bet for some to install in light duty enviroments
A bit of loctite - removable thread locker ( ligh tblue stuff ) also will act
to prevent the set screw from rusting into place. Some prefer to replace
the set screw with a set bolt ( square headed set screw )
should work ok - except in the heaviest of ice conditions
then it may add to the force required to break the ice away
from on top of the tower
When tightning the eccentric ring use the proper ring spanner to get it
seated tightly without damage to the spanner pin holes in the ring.
will make future work a lot easier - The right tool for the job.
Regards
Gerald Caouette
9116 - 79 street
Edmonton, Alberta
Canada
T6C 2R4
ve6nap@ve6nap.com
http://www.ve6nap.com
-----Original Message-----
From: K7LXC@aol.com [SMTP:K7LXC@aol.com]
Sent: Tuesday, January 23, 2001 11:47 AM
To: k0myw@worldnet.att.net; towertalk@contesting.com
Subject: Re: [TowerTalk] Thrust bearing preference
In a message dated 1/20/01 6:37:31 PM Pacific Standard Time,
k0myw@worldnet.att.net writes:
> I am preparing to sprout some antennas from a recently erected U.S.
> Tower HDX-555 crank-up.
> While I am VERY PLEASED with all other aspects of the tower and
> associated U.S. Tower hardware, I have a slight reservation about the
> TB-2US thrust bearing. I'm no expert in such matters, but that thrust
> bearing just doesn't look "right" for rugged outdoor service, laying
> flat atop the tower...
> So I'm wondering:
> Should I consider substituting a thrust bearing that more obviously is
> purpose-built for tower-and-mast application, such as one from Rohn,
> Yaesu or the new Glen Martin TB-25?
Hi, Mike --
Since it looks like no one else has answered your question, I'll take a
run at it.
Generally, pillow-block type bearings (they're not galvanized and
typically have one Allen set screw) are intended for indoor applications and
aren't suitable in the longterm outdoors. What happens is that the Allen
screw rusts and you have to drill it out in order to remove the mast - not a
pleasant job. The US Tower ones I've seen seem to be better in that respect.
> Or should I just continue to follow LXC's Prime Directive and "do what
> the manufacturer recommends" (in this case, use the tower
> manufacturer's thrust bearing)?
In this case I'd go with the US Tower bearing. The top of the tower is
already drilled for it and they seem to be okay reliability-wise. I'm not too
excited about one little Allen screw holding the mast load but you don't have
much choice. You might want to consider not tightening the Allen screw and
having the rotator take the vertical load by just having the TB function as a
bushing that supports the mast for sideloads.
I use the Rohn TB-3 (2") and TB-4 (3") for just about everything else. I
think the GME one is cast aluminum and isn't as rugged as the Rohn. It also
looks like the Yaesu one so it might come from the same manufacturer.
Cheers, Steve K7LXC
Tower Tech
--
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|