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Re: [TowerTalk] HF winch

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Subject: Re: [TowerTalk] HF winch
From: Jim Lux <jimlux@earthlink.net>
Date: Mon, 03 Feb 2014 07:43:48 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
On 2/3/14 7:14 AM, Mike Reublin NF4L wrote:
Great Jim, thanks!

Lets say 1200 lbs., length of 32' including mast.

So 1200 x 32 / 10 = 3840.

Cos(0) = 1, sin(45) = .707

3840 x 1/.707 = 5430 lbs. initial pull, correct?

Halving that with a 2:1 pulley system = 2715 lbs., a bit over the winch rating. 
A 3:1 pulley arrangement drops it to 1810. Do-able but close to the edge.

Mike NF4L


Sounds about right.

Bear in mind that every pass over a pulley adds some drag, not so much from the pulley bearing (which is negligible with ball bearings) but from the flexing of the cable.

What's the winch rating?  And is that with empty or full cable drum?
These little details often don't show up in the descriptive copy... but as cable piles up on the drum it increases the effective diameter of the drum, reducing the maximum pull force. Manufacturers like to give specs with the drum empty (all the cable pulled out). For a small winch with a 2-3" diameter drum, that fills up to 4-6" when full, that's a 2:1 difference in pull force.

Does the winch have a ratchet or self braking scheme to prevent it from freewheeling and paying out the cable if you lose power? (e.g. when the circuit breaker trips)


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