On 27/05/2021 14:25, The Natural Philosopher wrote:
On 27/05/2021 10:55, Roger Hayter wrote:
On 27 May 2021 at 10:34:42 BST, "nightjar" wrote:

On 26/05/2021 12:54, GB wrote:
Â* One official told Italian TV channel Rai 3 that the suspects had
Â* admitted disactivating the emergency brake following "malfunctions in
Â* the cable car", which repair workers had been unable to fix,
according
Â* to Ansa new agency.
Â* https://www.bbc.co.uk/news/world-europe-57252289
Â* As one does, of course. What a load of plonkers.

The cable that broke would have been a multi-strand cable. That is to
ensure that the failure of a single strand does not release the car. It
also means that it is very unlikely that all the strands will fail at
the same time. I wouldn't be surprised if they found signs of
progressive partial failures in the cable, which might be what was
triggering the emergency brake.

The purpose of being multi-stranded is so they can be wound round a
drum (or
generally so they are stronger when flexed because a solid cable would
have
excessive tension in the outer side even with bending under its own
weight).
But otherwise I agree the failure *might* have been progressive.

the purpose of stranded cable has nothing whatever to do with being
wound on a drum.

Of course it does.

And everything to do with the failure of one strand nit propagating a
stress fracture throughout the whole cable

That is also true, and a benefit, but I would like to see you deploy a
"single stand cable" (or steel bar as we might otherwise call it!) that
can be strung up through the winding gear for a cable car.

all suspension bridge cables are multi-element - strands or chain links
- for this reason. They aren't wound on drums

Apart from those that are solid links or rods of course.

Have you ever though of how you would get your solid half mile long
"cable" on site when building a suspension bridge if you could not coil
it and deliver it on a drum?


--
Cheers,

John.

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