Re: Modern high speed steam to Mackay.

[matthew@mail.usyd.edu.au (Matthew Geier)]

In article <36523EB0.7FC7CDFC@nmit.vic.edu.au>,
David  <david@nmit.vic.edu.au> wrote:
>Weren't they BO CO's,  one bogie was Electric, the other Deisel Electric ? I
>suppose the electric conversion would be too difficult to build a proper
>hybrid. Wouldn't it save on costs if it did use the electric overhead when
>possible ???

 Been done. Many times. "ElectroDiesels' operate on the east coast of the
US and in the UK. I think a few 'trip train' hybrids are also used in
Europe and Sth Africa.

 The US case is due to a a NY city bylaw banning steam (& diesels) into
the city. Hence they added 3rd rail pickup shoes to an others standard
type of diesel.
 One of these types was a Co-Co due to weight problems, and it may have
been the steam heating boiler that was the reason for the extra axle.

 The british electro-diesels I think are also 3rd rail system beasts.

 Electrical wise, the low voltage DC 3rd rail power is probably feed 
straight into the electrical part of the Diesel-Electric and the diesel
switched off.

 The Europen and Sth African units are severly power limited due to needing
a step down transformer and rectifiers as well as all the usual DE junk.
The units are basicly trip train only units - they can work into non wired
sidings. The same railways now also have battery hybrid trip locos - they run
off batteries into the non-wired sidings.

 An electro-diesel tilt train would have severe weight problems - it would
need a 3000kw diesel engine AND a 25kv transformer, also rated at 3000+Kw.
Thats a lot of dead wieght to haul around - at speed. Also remember that
the diesel prime-mover will need to be pre-heated before being put under
load, so some extra wieght in lube oil and water heaters and circulating
pumps that operate independantly of the engine itself.

 In all you are probably better just building seperate DE and straight
electric locos, and swapping at Rockie!. With diesel fuel as cheap as it
is and no other environmental constraints, DE the whole way is quite
cost effective.