More heat damage
 

Apparently the heat is to blame for damage to the over-head power on
lines out of Liverpool Street.

I took the Central to Stratford and then walkd (yes, on the bloody
hotest day of the year so far) the rest of the way.

At Stratford I saw an intercity being drawn very slowly by by a diesel
untit, it's own eletcric having it's transome down.

Curiously the 16:10 that had been cancelled at Liverpool Street was
expected at Stratford at some point. ;-)

Anyway, anyone know the nature of the damage? Overheads stretching in
the heat? Or something more esoteric?

Matthew
--
Il est important d'être un homme ou une femme en colère; le jour où nous
quitte la colère, ou le désir, c'est cuit. - Barbara

http://www.calmeilles.co.uk/

More heat damage
 

In article , Acrosticus
writes
From: Matthew Malthouse
Date: 06/08/2003 20:13 GMT Daylight Time

Anyway, anyone know the nature of the damage? Overheads stretching in
the heat? Or something more esoteric?

Well, not too esoteric. The wire expands and contracts like everything else
acccording to temperature, but it needs a certain amount of tension as well so
that pantographs don't get round the wrong side of it and bring the lot down.

On occasional OHLEs you'll see an assembly with removable weights that are
connected to the overhead to tension it. These weights are slotted onto a bar
and plate arrangement. If you can't get enough weights on the bar to remove the
sag (and, after all the bar has a finite length so it'll happen some time)
you're not tensioning the wire enough so it will sag, probably bounce as trains
pass underneath and could allow the panto to "wrong side" it thus pulling the
lot down.


IIRC the OLE out of Liverpool Street is pre tensioned and does not have
the weights you mention to re tension it when it stretches. I think once
one gets past about Gidea Park there is tensioning.

--
John Alexander,

Remove NOSPAM if replying by e-mail

More heat damage
 

On Wed, 6 Aug 2003 22:35:04 +0100 John wrote:
} In article , Acrosticus
} writes
} From: Matthew Malthouse
} Date: 06/08/2003 20:13 GMT Daylight Time
}
} Anyway, anyone know the nature of the damage? Overheads stretching in
} the heat? Or something more esoteric?
}
} Well, not too esoteric. The wire expands and contracts like everything else
} acccording to temperature, but it needs a certain amount of tension as well so
} that pantographs don't get round the wrong side of it and bring the lot down.
}
} On occasional OHLEs you'll see an assembly with removable weights that are
} connected to the overhead to tension it. These weights are slotted onto a bar
} and plate arrangement. If you can't get enough weights on the bar to remove the
} sag (and, after all the bar has a finite length so it'll happen some time)
} you're not tensioning the wire enough so it will sag, probably bounce as trains
} pass underneath and could allow the panto to "wrong side" it thus pulling the
} lot down.

So was the disruption precautionary or was there actually an incident?
The info sceens yesterday afternoon calimed problems at several places.

} IIRC the OLE out of Liverpool Street is pre tensioned and does not have
} the weights you mention to re tension it when it stretches. I think once
} one gets past about Gidea Park there is tensioning.

I recall tensioning weights at Forest Gate but can't at this moment
swear that they are still there - memory might well be from before the
section had the overheads renewed a few years back.

This morning most seemed back to normal although there was one
Shenfield bound service around half seven marked as canceled.

Wonder what it'll be like this afternoon. :(

Matthew
--
Il est important d'être un homme ou une femme en colère; le jour où nous
quitte la colère, ou le désir, c'est cuit. - Barbara

http://www.calmeilles.co.uk/