[TowerTalk] ratings on wire rope

[Jerry Keller]

"I had a Hunter's block and
tackle I've elevated 25 elk on."

25 at one time? That's some block & tackle....

K3MGT

----- Original Message -----
From: <K7GCO@aol.com>
To: <towertalk@contesting.com>; <alwilliams@olywa.net>;
<w7jwj@contesting.com>; <k4vx@arrl.net>; <K6myc@aol.com>
Sent: Wednesday, September 05, 2001 3:06 AM
Subject: Re: [TowerTalk] ratings on wire rope


>
> In a message dated 9/4/01 7:49:51 AM Pacific Daylight Time,
> alwilliams@olywa.net writes:
>
> <<
>  >     Picture a pulley up on your tower and you want to pull a 1,000 load
>  with
>  > a rope that goes through and down to the ground where you're going to
>  pull.
>  > The load on the pulley is 2,000 pounds - 1,000# on the load side and
>  1,000#
>  > on the pull side.
>  > >
>
>  A questions for the physics experts -- Is it true that in order to pull
up
>  the 1000#
>  load that the pull will have to be 1000# plus the amount to overcome the
>  loss
>  due to the pulley efficiency?  What is the efficiency for a typical 3 to
5"
>  pulley
>  of various bearing designs?
>
>  k7puc
>   >>
> All question are worthy of some kind of an answer.  I have to ask why the
> efficiency of 3 to 5" pulleys of various bearing designs is a question?
> Bearing drag percentage wise has got to be very small.  I obtained some
> pulleys from Boeing Surplus and made a series of block and tackles with up
to
> 5" wheels.  Many tried to buy them off me.  I said "they were just for
show
> and tell."
>
> Here is a case where wheel drag was important.  I had a Hunter's block and
> tackle I've elevated 25 elk on.  I started using it on lifting the 20'
mast
> with a beam on top to get access to my PP motor or other heavy loads.  It
got
> so that the pull on the rope with a 4/3 pulley was more than the weight of
> the load--or seemed like it?  I took it apart to find out why it had so
much
> drag.  Over 40 years dirt had accumulated between the no bearing wheel and
> the side plates so bad it was like a brake shoe with a fair friction.  I
> cleaned it all out and installed 3/4" bearings in each wheel.  What a
> difference!  I could literally pull on the rope with 1 finger and lift a
> heavy load.  Here was a "worst case of wheel drag totally reversed."
>
> I have an application for block and tackles outside permanently.  I'm
looking
> for sealed bearings that will resist wind blown rain.  Does anyone know if
> that oil impregnated bearing bronze is available in tubes say for a 1/4"
> bolt?  It would make a great outside bearing for block and tackles.  k7gco
>
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>
> -----
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>


List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!!  http://www.anwireless.com

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