This is something I have been looking for amongst my junque, and finally came across it the other day. It is a few pages out of the June 1994 issue of Railfan & Railroad, and article called "Steam versus Diesel - Today!" by Rich Melvin.
Not sure of the "kosherisity" of copying any of it over here without permission from R&R. However, if you can find copies of that issue on ebay, etc., or dig through your old copies, it is a worthwhile read.
Melvin tells of his adventures running Nickel Plate 765 over the road with diesel-era road foremen aboard. As he says, every line had "The Hill" and most of the diesel guys were concerned that the steam loco would not have the where-with-all to do the job without a helper. Melvin, along with Gary Bensman, John Snyder, Kim Besecker, and others, put on a workshop on the capabilities of modern steam power.
As a bonus, there is a separate section by Jack Wheelihan on the running of SP 4449 in similar conditions.
One incident related the 765 tackling a 1-percent grade near Attica, NY. The road foreman was quite edgy, thinking they needed a helper. The train was 24 cars. Well into the grade, and doing fine, the air went into emergency, the result of broken air hose. After a stop and repair, it was truth or consequences! No slack. On a grade. Get her started. The road foreman was in a dither.
With Snyder firing, the story went, " I dropped the reverse into the corner, opened the sanding valve and cracked the throttle. The steam chest pressure began to climb ... John had her sizzling at the pops with steam pressure on the nose at 245. I widened out further on the throttle until it was wide open, and the cylinder pressure had reached full boiler pressure. But we hadn't moved yet!"
Now the worry was to watch for a slip and be ready to "slam the throttle home." Slowly, without slipping, they could detect forward movement. Before reaching the summit, they were at 30 mph.
It seems this would be a great article to copy and laminate for budding steam engineers and firemen. The understanding of monitoring cylinder pressure, watching for slipping, and controlling a locomotive over a demanding route, speaks volumes. There are also accounts of running the New River Train with 36 cars, plus a comparison with a 3,600 hp Dash 7.
Anyway, the article is recommended. It is a hackuva lot of fun!

I tried attaching another piece that was tucked in with the article, but it was too large to post. Not sure of its provenance, but it sounds like from a live steam modeler.
Here are some paraphrased excerpts:

Factor of Adhesion
The factor of adhesion is how much weight is on the drivers divided by tractive effort; note tractive effort is calculated based upon the cylinder size, number of power strokes per revolution of the drivers, max. allowable working pressure, and driver size. It has nothing to do with the weight of the loco or the number of drivers.
Locos aimed for a Factor of Adhesion of 4, meaning 4 pounds on the drivers per pound of TE. If loco has 30,000 pounds TE, it should have around 120,000 pounds on the drivers. Adding more weight to the drivers does not change the TE -- it increases the factor of adhesion meaning that it is easier to apply more power to the rails. A 2-10-0 can have the same TE as a 2-8-0, but the axle loading could be less to help alleviate loads on the track structure.

I recall seeing Canadian National employee timetables with charts on this for different routes, depending on the ruling grade.

I recall reading about UP 844 on a ferry move (with train) coming up behind and pushing a stalled freight (one unit was down), bunching the slack (still with its own train) until stopped with 300 psi and no motion and no slipping. The head end started pulling and eventually 844 started moving, still no slipping.

Steam locomotives have reciprocating engines whose horsepower goes up with the rpm. Since they are direct drive, the rpm and the speed are directly related. Thus the faster a steam locomotive goes the greater the horsepower.

In the late 1940's when 2-8-4's were competing with F3's the axiom was "a diesel can start a train it can't pull while a steam engine can pull a train it can't start."

Phil Mulligan

Mr. Berry,
Thank you for the response.
Last night, I was looking through Donald R. McQueen's excellent book "Canadian National Steam." He was comparing the CNR Northerns with the CPR's standard Hudsons. One would have to look up the stats, but they were very close. CNR liked the extra axle for its trackage conditions. That goes with the post on factor of adhesion.
So as not to have this thread accused for "railfanning," I was hoping that some with hands-on operating experience with main line steam power would chime in. A good friend, when talking about steam technology, often uses the word "nuances." In other words, the nuances may be lost for locomotive repair and operation so many years after the fact, and with most of the old steam men gone.
From casual observations--and I am certainly no expert--there seems to be a need for modern operators to learn more about "first principles" in repair, maintenance, and operation over the road. That is not meant as a criticism, rather as an observation that younger operators might need guidance to learn all those nuances. The 1994 article certainly shows what can be done by experienced operators.

Rich talked about this incident in New York on the FWRHS's youtube channel. The video can be found here:
https://www.youtube.com/watch?v=GN_NYiN6NPU

There is a video of this is on Youtube: UP 844 Assists a Stalled 11,620 Ton Freight Train!!!