>David Johnson (trainman@ozemail.com.au) wrote:
>>Maurie Daly wrote:
>>
>>> This leads to various differant HP ratings that can be delivered to the
>>> traction motor sets at differant speeds and for differing times.
>>> Ideally it would be nice to be able to increase the number of traction motors
>>> from the usual 6 to 8 as engine HP increases,but loading and curve radii
>>> prevent this.
>>
>>A couple of observations I'd like to share. We ran a 105 wagon coal train from
>>Kooragang Island to Ulan and return. On the return, we did a test lift on
>>Whittingham Bank with three 90 class locos and 11670 tonnes hanging off the
>>back. At 0.5 km/h, the locomotives were exerting about 300 horsepower at 1900
>>Amps. At 2 km/h, the locomotives were exerting about 900 horsepower at 1800
>>Amps. At 25 km/h, the locomotives were exerting about 3830 horsepower at 900
>>Amps.
>Do you happen to know what the tractive effort at the same speeds was?
>Cheers
>David
These numbers translate to tractive effort (in good old-fashioned
"pounds mass") and at constant speed to
360,000
270,000
92,000
So something seems a bit screwy here. It depends on what you mean by
"exerting"..... at the wheel, at the generator. It also depends upon
what degree of accelaration there was: to accelarate an 11670 tonne
train (about 12,000 round figures when you count the locos) at 0.3 kph
per second requires about 6,000 HP total at about 10 kph. Also, what
is the grade of Whittingham (I don't have my grades book in front of
me)? A 1:100 (1%) grade requires a tractive effort of 1% of 12,000
tonnes to hold the train, i.e about 270,000 lb.
Geoff Lambert