Hi Gregory
On (01 Aug 97) Gregory Procter wrote to Alec Cameron...
 GP>       sorry, the World distracted me from our sparring match there for a
 GP> bit!
The World is like that!
 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.
Not now! It was in 1985 that we had visits from Brown Boveri to where I
    ^^^
worked, they wanted to sell us that kind of technology for power station
motors in the range 5000 to 20 000 hp for electric feedpump motors and such.
They showed designs for working locos using variable frequency drive. Our
practice was to use either, constant speed motors with automated [water]
valve control, or hydraulic couplings, or slipring motors- each very
inefficient ie energy wasteful.
 GP> Better equalization would have been more effective!
 AC> Whoa! Explain Better Equalization in this context....... please.
 GP>       That's no problem: Any bogie design is a compromise,
 GP>       1. Best equalization is probably 3 point,
 GP>       2. The bogie pivot point should be at rail height, and
 GP>       3. Axles should swivell to run at right angles to the rail.
 GP>       4. Tractive effort needs to be transfered at rail height.
Thanks. I can see that you know the geometry. Yes it's a bleeding compromise
and I fear that the steam version is the most compromised of all!!
 GP>       to haulage bogies as yet.
 GP>       I don't know of any railway that mounts its couplers at rail 
height,
NSW Railways headed in that direction, with Co Co electrics of 3780 HP 
1953].
These had the bogies coupled together, the drawgear on the bogies' ends. The
body was a lightweight "shell" as it had no buffing loads to carry. One bogie
was pinned to the body [king pin] and the other bogie had a slider. So when
cornering on tight radii, one end of the body would stay above the track
locus, but the other end of the body would pitch toward the lateral limit of
the loading gauge.
 GP>  No, I was thinking along the lines of a Diesel Hydraulic chassis, ie
 GP> bogies
 GP>  driven by cardan shafts and gearing, with a high speed steam motor
 GP> in the
 AC> Maybe your next message will say- steam motor? Turbine or what?
 AC> ^^^^^^^^^^^
 GP>       I'm not sure of your point here?
Well, I don't know what you mean by steam MOTOR. Reciprocating engine? Cross
compound? Vee 12? Turbine?
 GP>       Cardan shafts are commonly used on Diesels and Electrics (Europe) 
to
 GP>       reduce the unsprung weight on wheelsets. eg TGVs have the electric
 GP> motor
 GP>       on the mainframe driving each axle by cardan shafts.
A great solution, if the traction motor is huge and heavy.
See ya in the next message>>>>>>>>>.
... 
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