Re: C Class Rumours

[G.Lambert@unsw.edu.au (Geoff Lambert)]

David Bromage <dbromage@omni.com.au> wrote:

>TM wrote:
>> The NSW WTT shows the following weights:
>>                      Dead Weight                   Live Weight
>>                           Tonnes                           Tonnes
>> C class                 148                                   134

>The dead weight isn't the actual weight, i.e. the force on the rails due
>to gravity acting on the mass. The "dead weight" takes into account the
>additional resistance of the dead traction motors.

Gee, I've never noticed this before, what WTT was it in, and is there
a list of similar statistics for other locos?

Of course, this increased resistance masquerading as increased mass
(or for the purposes of train loads being assumed so) would be
speed-dependent, would it not?  Presumably the value given is some
kind of average based on the likely speed range.  

When a D-E loco is hauled dead and the traction motors are spinning,
is there eny emf component to the resultant resistance?  If so, and if
voltages appear at the terminals and currents come out of them, where
and how are they dissipated?  Or do you need excitation current to be
present for this sort of thing to happen?

Geoff Lambert