Re: C Class Rumours

["Rod" <berlina@bigpond.com>]

>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
Never seen any mention of dead weights and live weights in Victoria, this
must be something in other states.
As a driver I can tell you that a 60 tonne Locomotive is harder to haul than
say two louvers, all up 60 tonnes.
Modern Locomotives using relays operated Electrically will not generate any
energy being hauled as all relays will be open, and no circuit will be
completed.
The resistance is solely the (4) traction motors being spun on their white
metal bearings, and the design of their gearsets which retard when spun
without energy being applied. This retardation will be enhanced by turning
the motors into generators, when the loco is on line, and by turning this
energy to traction motor blowers or shorting the current into Dynamic Grids
and cooling fans there-to fitted [called Dynamic Braking]
On older locos such as B class, here in Victoria, the Electrical System uses
Air operated relay sets,
which will remain set-up, even when the loco is shut down. To dead tow one
of these locos, we would rotate the reverser drums manually to a position
that isolated the traction motors and allowed them to turn, with minimal
resistance.
Hope this helps
Rod :o)