Steam

[NW Mailing List]

Please email me at johntrhodes at gmail.com and I will send you some things.

On Sun, Jun 1, 2008 at 3:52 PM, NW Mailing List <nw-mailing-list at nwhs.org>
wrote:


>

> > I didnt say max TE was determinied by power output of the prime mover.  I

> > said a DE needed more primemover output to get max TE than a steam loco.

>

> Any equations or graphs to show the above, preferably with verified sources

> (i.e, the EMD chart showing engine rpm, total hp, net traction hp, fuel rate

> (lbs/hr(gal/hr), and duty cycles for each throttle notch) for whatever

> diesel you're referring to for comparison?  If you need one, I have them for

> the SD50A(1984 16-710G), SD60(1991 16-710G3B) and GP59(1988 12-710G3A)...

>

>

> > Maybe I should have been more in depth.  In terms of cylinder TE it

> remains

> > the same till the cutoff has to be reduced when the boiler can't provide

> > enough steam to allow full cutoff.  TE at the rail is limited by

> adhesion.

> >  So if the cylinder size is set to allow the maximum desired TE to be

> > produced at the max speed in which the boiler can supply enough steam to

> > allow full cutoff then all of the preceding speed range will have the

> same

> > rail TE limited by adhesion.  The cylinder TE could be hire but is

> limited

> > by adhesion.  The drawbar pull however would be less at say 10 mph due to

> > locomotive resistance which must be subtracted from te to get Drawbar

> pull.

> >  The locomotive resistance at 10 mph would only be a few thousand pounds

> > though.

>

>

> Again, any equations to show the above, specifically, TE at the rail at x

> mph?  What is 'Cylinder tractive effort'?  I fail to see how a cylinder can

> produce tractive effort given that it is not in contact with the rail, nor

> does it transfer weight to the rail... or do you mean torque?



I mean Cylinder TE which doesn't include the resistance of the reciprocating
parts of the engine.



>

>

>

> >> D: While drawbar horsepower will fall as speed increases (darn that

> >> physics), the diesel is applying full power to the rail throughout it's

> >> speed range.

> >

> >

> > Irrelevant a diesels DBHP at 0mph is still 0

>

>

> Yes, that's true, but using that as an argument for irrelevance is quite

> odd, as at nought mph TE and DBHP are also nought for any locomotive type...



Max TE is produced at 0 mph just before movement happens.

Both steam and diesel are constant horse power machines.  The max hp of the
prime mover of a diesel can be maintained continuously even if the current
would damage the traction motors. and A steam locomotives boiler can
maintain its max boiler horsepower continuously even if it is escaping from
the safety valves.  Neither locomotive or any other produce constant drawbar
horsepower from 0 mph it is physically impossible.

What I am saying is the force available at the coupler face (drawbar pull)
is all that matters to run a train all this other stuff doesn't mean a thing
and has been used as marketing hype.



>

>

>

> > This doesnt have to be don't have so high a max DBHP and keep the

> starting

> > TE inline with a diesel.

>

> Same answer as the the first part...

>

>

> Robb Fisher

> RFDI

>


John Rhodes
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