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Re: [TowerTalk] New Sheaves for Crank-Up

To: N3AE <n3ae@comcast.net>
Subject: Re: [TowerTalk] New Sheaves for Crank-Up
From: Grant Saviers <grants2@pacbell.net>
Date: Fri, 23 Aug 2013 18:00:27 -0700
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
No experience with wire rope on nylon, but you might consider the UV degradation of nylon as a drawback, particularly since one segment of the sheave is exposed for long periods. (assuming you leave your tower up most of the time).

Did the ball bearings seize up and cause the excessive wear?

Grant KZ1W


On 8/23/2013 5:43 PM, N3AE wrote:
Hello tower experts,

I'm in the process of refurbishing an old EZ-Way crank-up and looking to replace some lift cable sheaves 
which have excessive wear in the ID of the groves. The current 3" OD metal sheaves are sized for 
3/16" cable. The sheaves are rather narrow, measuring 0.38" at the rim and 0.45" at the 
hub where the ball bearing is pressed in. The tower sheave brackets will only accept a maximum sheave 
width of 0.50", and that's tight.

While looking at McMaster-Carr's web site ( 
http://www.mcmaster.com/#wire-rope-sheaves/=o71onb ), I was surprised to see 
Nylon sheaves for wire rope applications. For the size I'm looking for, they 
have the same load rating as the metal sheaves shown near the top of the web 
catalog page.

Does anyone have experience with using Nylon sheaves in the lift systems for 
crank-up towers? Somehow, this seems wimpy to me, but they do meet my max width 
requirements and have the same load ratings as similar sized metal sheaves.

I've found another source that has what I need in stainless steel (with a 
bronze bushing rather than a ball bearing), but still curious about the Nylon.

Thanks

Shawn - N3AE
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