AC>On (02 Jul 97) Reggie Arford wrote to Gregory Procter...
AC> But, some of your comments to him were aimed at my message
AC> so I will add to the discussion:
AC> RA> steam locos do not have "a" rated horsepower as a Diesel does;
AC> RA> they cannot. As any motor turns faster, its power increases (up
AC> RA> to a point).    ^^^
AC>Quite wrong! Most electric motors [both AC and DC] reduce in power
AC>output as the speed increases.
Well, yes, but at zero speed power is (by definition) zero; at
some small speed, power is more than zero. As I say, "up to a point".
For an electric motor, at low speeds, the controlling parameter is
the current that can be applied.
AC> RA> Why? A Beyer-Garatt (sp?) type engine, perhaps burning
AC> RA> pulverized coal or a coal/water slurry, would work quite nicely.
AC> RA> Note that on a steam loco, the axles are usually MUCH closer
AC> RA> together, so a 4-coupled steamer may have a similar rigid
AC> RA> wheelbase to a C-type (3 axle) traction truck.
AC>These two versions of "rigid" wheelbase can hardly be compared because the
AC>springing of the individual axles on the C- type track assures more 
constant
AC>force on the wheels, than is possible with the steamer. Over rough track 
[is
AC>there any other kind?? ]  the rigid steam drivers will often have two 
or
AC>more wheels barely in contact with the rails, as the loco shimmies and 
bumps.
AC>The C- truck is far from rigid, one axle may rise while its partner falls,
AC>thus maintaining hefty contact with the [slippery?] rail. A bit like
AC>independent front suspension on an auto, versus beam axle.
Err, no. On a steam locomotive, all axles are typically fully
sprung and equalized. The equalizing system adjusts the spring
tensions so that all axles receive their share of the burden.
Note that lead and trailing truck axles are typicaly included,
but at a lesser rated burden.
AC>Well, this is theory and dreamtime.
Sure. Until someone needs one, and builds it. Just how much
longer will it be economical to burn oil, vs. coal? :)
Reggie Arford
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 X SLMR 2.1a X Sometimes the best solution is what worked last time.
--- Maximus 3.01
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