Steam

[NW Mailing List]

> 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?



>> 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...



> 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