Not to minimize your friend's death, not at all.
Speaking technically, this may mean that stretchy rope should not be
used with severe loads, or with heavy loads on pulleys using friction
or sleeve bearings.
The 4:1 stainless ball bearing halyard pulley set I got from the
marine supply house does not exhibit the jumpiness you reference. The
pull across it is completely smooth. I would not use pulleys that
exhibited the behavior you described, assuming, due to the friction
exhibited, that the bearings were overloaded.
As has been explained, there are some load positioning advantages to
rope with a slight stretchiness.
I have seen some degree of the phenomenon you describe on a rope
pulled by a car with a standard transmission. The clutch action was
too jerky. They changed to a car with an automatic transmission and no
more problem. Any non-gradual change in movement is a problem.
In any event, people can get killed on and around towers. If ANYTHING
seems weird, cease and desist until everything is properly worked out.
It really is tough losing a friend in an accident. All of a sudden
they're just gone, there's this big hole in your life, and there's
this unreal circumstantial mess to help clean up.
Ain't NUTHIN on a tower worth risking that.
----- Original Message -----
From: "Ronald KA4INM Youvan" <firstname.lastname@example.org>
To: "tt" <email@example.com>
Sent: Sunday, June 16, 2002 12:05 AM
Subject: Re: [Towertalk] rope
> > There is NOTHING wrong with using nylon rope.
> I'm afraid there is a fundamental problem with using any stretchy
> rope as a load line on a tower. Many tower workers (including a
> friend of mine) have died because of this situation.
> With a safe but heavy load, the rope stretches as the load line
> is taken into the hoist,* when the top pulley friction is exceeded
> the load will jerk up, reducing the stretch on the hoist side of
> the top pulley, this action repeats and the load jumps up in steps.
> When the stretch in the load side of the line jumps over the
> reducing the stretch on the hoist side increasing the stretch on
> the load side, followed by the load jumping up and settling down,
> stretching the load side of the rope even more, the rope on load
> side can be stretched with forces that exceed the breaking strength
> of the rope and it can break.
> * or pulled by truck or tractor
> 73 (= Best Regards) de: Ron firstname.lastname@example.org
> 100% LINUX, since July, 1997 SENT Time and Date are UTC
> Visit my HAM Web SITE at: http://www.qsl.net/ka4inm
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