[TowerTalk] US Tower HDX-689 Sheave replacement

[Grant Saviers]

There are many KP8 and KP10 bearings on ebay, but I do note they are 
surprisingly expensive if you want a premium brand.  Chinese versions 
are much cheaper.  However, the pictures show different size KP bearings 
so checking with the seller about the bearing dimensions is probably 
necessary.

I've found that ebay, McMaster.com and MSCdirect.com have virtually all 
of what I have needed and are far easier sources than chasing around to 
local bearing suppliers to see what they have in stock. MSC has the 
larger selection.  Grainger is another source but usually only deals 
with businesses.

The first step is to measure what is being replaced, ID, OD, outer race 
width and inner race width.  A $10 digital caliper from Harbor Freight 
is all that is needed.  Then to decide if the bearing is inch series or 
metric and look at the catalog web pages.

It seems a bit unusual to use a ball bearing in a weather exposed 
application such as the UST sheeves.   There are some stainless steel 
ball bearings, but a very limited set of choices.

Peening the sheave to lock the bearing outer race seems a bit strange.  
However given the KP series wider inner race it seems they are 
"cheating" and hoping the peening locates the sheaves laterally on the 
bearing outer race.  Yuk!  The sheaves have a lot of force on them so 
peening seems a marginal means to keep them from walking laterally on 
the outer race.  And peening against a ball bearing race??  A sure way 
to dramatically shorten its life.  It seems UST is doing something 
"creative".

When I get a chance I'll make some measurements and think about a 
possible better way.

Grant KZ1W


On 3/11/2013 6:23 PM, Bob K6UJ wrote:
> Rich,
> I should have read your message before posting.  I was going to call US Tower about the bearings too.  I have a HDX589, the K10 bearings must be what I need.
> Now to find some !!!
>
>
> Bob
> K6UJ
>
>
>
> On Mar 11, 2013, at 5:30 PM, Rich Hallman - N7TR wrote:
>
>> I tried calling US Tower all day...but phone just rang.  Not sure if there is a holiday somewhere that they didn't come to work today.
>>
>> I found that the bearing inside the sheave is a K10 bearing.  Looks like a KP10 bearing might work but these seem to be REAL hard to locate.
>>
>> Thanks for all the ideas from the list.  With the amount of towers out there, I was hoping for a stock replacement solution, but looks like this is a bit more complicated...or expensive.
>>
>> Rich
>>
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Rich Hallman - N7TR
>> Sent: Sunday, March 10, 2013 5:19 PM
>> To: towertalk at contesting.com
>> Subject: [TowerTalk] US Tower HDX-689 Sheave replacement
>>
>> Im looking for the 5 inch OD Pulley Sheave for the HDX-689. This is for the ¼ in cable.   I need to order a few of these as I'm replacing all the cables on the tower right now.  I know US Towers had them, but wanted to see if anyone else has replaced them from another vendor for a better price.
>>
>> Thanks...
>> Rich
>>
>> Rich N7TR
>> ex KI3V, N3AMK, WB3JOV
>> www.n7tr.com<http://www.n7tr.com>
>> http://www.qrz.com/db/N7TR
>> Telnet: dxc.n7tr.com N7TR DXCluster
>>
>>
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