Re: Flat locomotive batteries question

[telljb@ozemail.com.au (< Tell >)]

"Donald R Smith" <drsmith@iinet.net.au> wrote:
>
>Most of the contactor switching is by air.  In a lot of locos the
>compressor/extractor works off the main shaft.  If the donk isn't running
>then there's no air.
>Actually when I first saw this question I thought it's not as silly as it
>sounds.
>However, all of the circuitry is designed for things to happen the other way
>around..
>Just pull the main switch.


Right on about the main switch.  

As for the contactor switching by air, the NSU class of
CR have a small air reservoir for just that purpose.  
I discovered that if the isolation valve next to the
reservoir was isolated, you could start the loco
without building up air via the compressor which was
battery run and mandatory before attempting a start.
In other words, you save the drain on the batteries by
building up air first before attempting a start.

The NSU class while Swiss Sulzer powered, showed their
English ancestry by leaning heavy on the batteries
before attempting a normal start.

The Brits back then, never quite discovered LV 
(Low Voltage) contactor switching for start up.  
They relied on air which has a habit of "escaping".

That.. in a small way explains why even today, the UK
rail industry has nothing to offer and why USA train
technology has succeeded.
  
----Terry Burton
Alice Springs NT