Re: Performance of XP Power cars.

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

In article <3557105E.825B6DAD@ozemail.com.au> David Johnson <trainman@ozemail.com.au> writes:
>Date: Tue, 12 May 1998 00:51:10 +1000
>From: David Johnson <trainman@ozemail.com.au>
>Subject: Re: Performance of XP Power cars.

>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.

>1) Were you using the dead weight, or the live weight of the deceased power car?
>(You have the added resistance of the traction motors in the rear power car.)

Dead weight  of 90 tonnes.

>2) You can take away something like 200 horsepower from the power car when it is
>being used as the power supply for lights and air-conditioning.  I remember on 1
>occasion when I was on NT23 to Tamworth, and one power car died in 40+ degree
>heat, so we turned off all air-conditioning and lights between Murrurundi and
>Ardglen, just so we had a fighting chance of making it up the hill without the
>assistance of the 3 35 class bank engines.

Could explain part of the problem , means there is only 1800 HP available for 
traction , although this still would be plenty enough, although the consistant 
failures of the locos on hot days seems to indicate that the design of the 
engine cooling system is deficient.
Diesel locos normally dont die on hot days, due to lack of cooling.
When the XPTs were originally derated from the normal 2200 HP of the HSTs was 
anything else derated as well , like smaller radiators etc.
Exactly how was the derating done , smaller injectors, less turbo boost , max 
RPM reduced ?

Maybe its time for a new engine , something like a cut down version of the 
GE16FDL model in the NRs .
With 8 cylinders you could still get 2000 HP , and it would be lighter than 
the Paxmans.

cheers
MD


>--
>David Johnson
>CityRail Guard
>trainman@ozemail.com.au
>http://www.ozemail.com.au/~trainman/