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Re: [TowerTalk] US Tower HDX-689 Sheave replacement

To: Bob K6UJ <k6uj@pacbell.net>
Subject: Re: [TowerTalk] US Tower HDX-689 Sheave replacement
From: Grant Saviers <grants2@pacbell.net>
Date: Mon, 11 Mar 2013 20:39:24 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
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@contesting.com] On Behalf Of Rich 
Hallman - N7TR
Sent: Sunday, March 10, 2013 5:19 PM
To: towertalk@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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