Here's a follow-up for those that might be reading this thread. Roger raises
some good issues (repeated below).
First of all, I don't intend to use nylon sheaves, but wanted to see if anyone
had experience with this material. With proper fillers, nylon can be made more
resistant to UV, but not enough to make me happy for this application.
The reason I want to replace the sheaves is that one pair on the mid-section
has excessive wear on one side of the groove ID. Measuring at the very top of
the groove to the outside of the sheave, one sidewall is 0.010" but the other
sidewall is feathered down to as small as 0.032" This is no doubt due to the
fact that the axis of rotation of these sheaves is not exactly perpendicular to
the line of force of the wire rope, so there's some side loading as the cable
runs onto the sheave. The misalignment ia about 3 degrees. Based on careful
inspection, it appears that the tower was fabricated this way and the
misalignment was not created by damage. A friend who also has an EZ-Way has
noticed similar sheave wear. Guess I could flip them around and let the other
side wear, but much rather replace. I bet a nylon sheave with this misalignment
would have one edge shaved off in short order. Maybe true for aluminum as well.
The bearings are in reasonable shape...rotate freely with just a bit of rumble.
The challenge in finding replacement sheaves for an EZ-Way is finding ones that
are not too thick at rim or hub in order to fit into the sleeve slots on the
tower. The originals (base of mid-section) measure 0.350" wide at the rim and
0.435" at the hub (across the pressed-in ball bearing). One sheave in the top
section (has a smaller 3/8 inch ID bearing) is only 0.375" at the hub...thank
goodness that one is OK.
After a lot of searching I found some stainless steel sheaves with oil
impregnated bronze bushings that will fit in the mid-section slots. Have not
ordered them yet. Guess I'll also have to change the sheave axles from hex cap
screws to shoulder bolts to keep the bushings happy.
N3AE
n 8/23/2013 8:43 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.
This is probably more for others than the original poster:
As others have well stated the life problems of Nylon, my question is
why do you want to replace the sheaves? Are they bad, or just the
bearings, or do you want to replace them with something more substantial?
If the sheaves are OK, but the bearings are in poor shape, I'd just
press them out and new, sealed ones in. I assume the originals are
sealed. Changing them only takes a small arbor press. For those not
familiar with pressed bearings, they need to be pressed in and not
tapped in with a hammer. You can do it, but risk damaging the sheave
and giving it a permanent wobble.
Brass was mentioned, but it's usually "Oil light" which is a porous
Bronze, not Brass. If the axle is a good fit and smooth these last
quite well even with an off center load as long as the off axis is not
extreme. OTOH 0.45" is getting pretty narrow for much off center load.
I've never seen commercial bearings of regular brass although I'm sure
they exist. I'd not expect them to be anywhere near as durable as "oil
light", or bronze bearings which you mentioned with SS sheaves.
Unless the originals have a history of problems, I'd stick with them.
It sounds like the hub is already as thick as you can get, so you'd gain
little but appearance with a wider rim.
73
Roger (K8RI)
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