Kevin--
I think you have it backwards. The cable should be sized to do its job, with
appropriate safety factors, and the motor limited to less than the danger
level. Bigger is NOT better, if it can damage things.
Bill-W4BSG
----- Original Message -----
From: <knormoyle@surfnetusa.com>
To: <towertalk@contesting.com>
Sent: Thursday, May 20, 2010 2:33 PM
Subject: Re: [TowerTalk] Motorized Crank Up Towers
>
> maybe someone can answer this for me.
> I've been thinking, that based on everything said, that cable corrosion is
> the main issue to worry about.
>
> Steve's example of motor-driven failures got me wondering about the max
> force a typical motor setup can put on a cable.
> Obviously there's gearing.
>
> The system has to be designed minimally for the tower weight, friction,
> and an unknown amount of antenna/mast/rotator/cable
> load. I suppose there's static friction to overcome from a stationary
> position also, so that's more.
>
> I'm wondering how much force the motor can put on the cable without
> stalling. Is it 2-3x the maximum force needed?
>
> If so, does that mean the cable broke at 2-3x working load?
>
> Or did the motor put 10x the working load on the cable without stalling?
>
> I'm wondering if the real issue was cable weakness, even if it was the
> motor pulling on it. I would think the numbers work
> out so that the cable should be able to tolerate the max force from the
> winch possible (even if tower is stalled). (assuming
> a new cable, not degraded by corrosion?)
>
> Don't know though. Thoughts?
>
> -kevin
> ad6z
>
>
>
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|