Re: Performance of XP Power cars.

[dbromage@metz.une.edu.au (David Bromage)]

Maurie Daly (mauried@commslab.gov.au) wrote:
>In article <3557105E.825B6DAD@ozemail.com.au> David Johnson <trainman@ozemail.com.au> writes:
>>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.

I thought the dead mass was 85t.

>>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.

The gross power off the Paxman Valenta 12RP200L is 1477kW (2000hp). There
is a maximum of 1353kW (1840hp) available for traction, or 1153kW (1570hp) 
when supplying auxiliary power. The class 43 (HST) has 1680kW (2285hp)
gross power, and is also 3.5t lighter than an XP. The XP radiators are
actually bigger to cope with the higher amibent temperatures. 

>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.

Janes shows 1500rpm max for the production Valenta. I don't know if this
was reduced for the XP, but idle speed when supplying auxiliary power is
1000rpm on the XP.

>Maybe its time for a new engine , something like a cut down version of the 
>GE16FDL model in the NRs .

I'm sure GE has a small Dash-9 engine which could easilly be adapted. The
other suggestion I had was inserting a powered trailer into the consist.

Cheers
David