Hi Alec,
      sorry, the World distracted me from our sparring match there for a bit!
       -=> Quoting Alec Cameron to Gregory Procter <=-
 AC> Hi Gregory
 AC> On (12 Jul 97) Gregory Procter wrote to Alec Cameron...
........
 GP> trailer over the mountains? You will want different gearing.
 AC> Yup, and alternative gear sets are offered for many loco designs, for
 AC> parallel reasons. The increasing versatility of loco electrics though
 AC> will surely lead to elec control changes, instead of gearing changes,
 AC> permitting mechanically identical locos being readily optimised for
 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 variable
 AC> frequency traction motors.
 This is only now becoming practical because it is at last possible to build
 motors and control gear with greater capabilities than required, so they 
ame
 be operated  at the maximum torque and horsepower that the running gear can
 cope with.
 AC> Some "smart" control systems apply less power to the lead axle, while
 AC> loading up those further back.
 GP> Better equalization would have been more effective!
 AC> Whoa! Explain Better Equalization in this context....... please.
      That's no problem: Any bogie design is a compromise,
      1. Best equalization is probably 3 point,
      2. The bogie pivot point should be at rail height, and
      3. Axles should swivell to run at right angles to the rail.
      4. Tractive effort needs to be transfered at rail height.
      Equalization is usually applied per bogie side, at best 4 point leading
      to unequal wheel loading on uneven trackwork.
      Co bogies equalize from one axle to the next, but not across all three
      axles so they will almost never carry equal loads.
      If the pivot height is not at rail height, any forward movement of the
      loco will tilt the bogie, changing the weights on each axle. As 
arranging
      the pivot at rail height is physically impossible, there must be some
      compromise here! The pivot also needs to be at the center of the
      wheelbase, which is not often achieved in 3 axle bogies.
      Swivelling axles are now possible, butI don't think they have been 
applied
      to haulage bogies as yet.
      I don't know of any railway that mounts its couplers at rail height, so
      another compromise in design has to be made.
 GP> It is quite hard to consider a modern steam loco, because there
 AC> are none. If by individual axle drive you mean electric motors, then
 AC> that is a gross abuse of the steam loco design process.
      That's been tried several times around 1900, but it seems rather 
pointless
      as a steam engine already has a drive able to deliver maximum torque at
      stall.
      A steam loco
 AC> should have a steam engine fed by its boiler. I too would like
 GP> another
 AC> steam loco design to be undertaken and more important! would like it
 GP> to
 AC> be applauded for its efficiency, durability, performance and low
 AC> running cost. I see not the slightest chance, that this will ever
 AC> happen. ====
 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 in 
the
 AC> Maybe your next message will say- steam motor? Turbine or what?
 AC> ^^^^^^^^^^^
      I'm not sure of your point here?
 AC> Cardan shaft? Great system it should be more popular. But I feel that
 AC> the ability of mu trucks to run with the [eg 6] motors at slightly
 AC> differing speeds and torques, due to dirty track or severe overload or
 AC> unequal wheel rim wear, is a PLUS in operation. When uncontrolled slip
 AC> occurs, it usually involves just one or two wheelsets, and those that
 AC> have gripped well, work significantly harder [pull more] while Slippery
 AC> Sam has let go.
 AC>
      Cardan shafts are commonly used on Diesels and Electrics (Europe) to
      reduce the unsprung weight on wheelsets. eg TGVs have the electric 
otor
      on the mainframe driving each axle by cardan shafts.
 >> CONTINUED IN NEXT MESSAGE <<
 AC> ... ....The wheel is environmentally unviable
 AC> -!- PPoint 1.92
 AC>  ! Origin: Bundanoon, Southern Highlands, NSW AUS (3:712/517.12)
  
... Catch the Blue Wave!
--- FMail 1.02
---------------