Re: Performance of XP Power cars.

[mauried@commslab.gov.au (Maurie Daly)]

In article <3557B79E.35B6@harnessnet.com.au> Craig Haber <albatross@harnessnet.com.au> writes:
>From: Craig Haber <albatross@harnessnet.com.au>
>Subject: Re: Performance of XP Power cars.
>Date: Mon, 11 May 1998 19:44:46 -0700

>Maurie Daly wrote:
>> Is there some additional derating of the XP power cars required when 1 dies ,
>> and why,or are these power cars not really 2000 HP.

>Something to consider though is tractive effort.  The aforementioned B
>or S are geared for max speed of 133km/h, compared to the XP at 180 or
>so, hence the B/S will have much better acceleration, and the higher
>tractive effort should be able to maintain higher speed on gradients.

>Cheers,
>CH.
>-- 
>Craig Haber
>albatross@harnessnet.com.au
>Manufacturing Systems Engineer (almost) 
>Web Page Designer, Harness Racing, Railways, and Essendon Football Club
>fanatic
>http://www.harnessnet.com.au/

Not really .
The tractive effort of a diesel electric engine rises as speed falls, and is 
at a maximum just above the stall speed , when the motors are operating in 
series.
At the speeds that the XPT should be making between Albury & Melb where for 
the majority of the trip there arnt any grades to speak of tractive effort 
isnt a problem. (motors running in parallel.)
After all an XPT with a dead power car still has about 4.5 HP/tonne , which is
more than enough to hit 115 km/h .
2.5 HP/tonne is needed for 115 km/h running on the flat.
Even south of Seymour there are only a few 1:50 grades , none of them long 
enough to have any adverse affect.
I just wonder whether the real problem is that the XP power cars may have a 
2000 HP engine , but that its simply not rated for continuos operation , as 
just about all diesel electrics are.

cheers
MD