-=> Quoting Alec Cameron to Gregory Procter <=-
 AC> Hi Gregory
 AC> either freight or IC passenger duty "at a flick of a switch". I am
 AC> thinking of the current large scale application of three phase
 GP> variable
 AC> frequency traction motors.
 GP>  This is only now becoming practical because it is at last possible to
 GP> build         ^^^
 GP>  motors and control gear with greater capabilities than required, so 
hey
 GP> came
 GP>  be operated  at the maximum torque and horsepower that the running gear
 GP> can
 GP>  cope with.
 AC> Not now! It was in 1985 that we had visits from Brown Boveri to where
 AC> I ^^^
 AC> worked, they wanted to sell us that kind of technology for power
 AC> station motors in the range 5000 to 20 000 hp for electric feedpump
 AC> motors and such. They showed designs for working locos using variable
 AC> frequency drive. Our practice was to use either, constant speed motors
 AC> with automated [water] valve control, or hydraulic couplings, or
 AC> slipring motors- each very inefficient ie energy wasteful.
They built the locomotives, but I'm not sure that they were entirely 
successful
in Europe, because the performance difference between a 200Km/hr Express and 

100Km/hr heavy drag was too great. It would have worked here in NZ where the
difference between a 100Km/hr express and a 100Km/hr goods is not that much 
;-)
 GP> Better equalization would have been more effective!
 AC> Thanks. I can see that you know the geometry. Yes it's a bleeding
Not really, I've designed/redesigned car suspensions and I'm playing with
model railway suspensions at the moment.
 GP>       I don't know of any railway that mounts its couplers at rail 
height,
 AC> NSW Railways headed in that direction, with Co Co electrics of 3780 HP
 AC> [1953]. These had the bogies coupled together, the drawgear on the
 AC> bogies' ends. The body was a lightweight "shell" as it had no buffing
 AC> loads to carry. One bogie was pinned to the body [king pin] and the
 AC> other bogie had a slider. So when cornering on tight radii, one end of
 AC> the body would stay above the track locus, but the other end of the
 AC> body would pitch toward the lateral limit of the loading gauge.
It was a fashion around that time. The trouble is, if you put the pivots at
railhead height where they should theoretically be, they tend to foul things
like railheads and etc. "Virtual" pivot points can resolve some of the
problems of course.
I'll get back to the motor design!
Greg.P.
  
... I call things as I see them; If I didn't see them, I make them up!
--- FMail 1.02
---------------