I was reading about the super-power concept of steam locomotives between the early and the modern ones. the earliest super-power from the 20s develop more horsepower and we're lighter. Like the B&A berksires from the 20s were able to develop over 76,000 pounds of tractive effort and weighed under 700,000lbs also requires lower boiler pressure. the NKP berks developed over 64,000lbs and weighed over 800,000lbs and requires higher boiler pressure.

I heard that the earlier super-powered berks had the 60% cut-off point which I guess that makes them stronger than the modern ones. So I guess that means builders removed the 60% cut-off if they did then WHY?

also why did the modern berks became heavier and less powerful than the earlier berks?

if the earlier berks were stronger and lighter then why go backwards?

any ideas?
Am I wrong?
I want to your thoughts

A couple things come to mind. First off, the tractive effort advertised is the maximum calculated (or measured in some cases) and doesn't take speed in to account. A lighter locomotive can have higher TE with the right drivers, cylinder and boiler pressure combination. My understanding was the earlier models had the power, but the later had power at speed.

2-8-4 development progressed over time.

The B&A A-1's were the first production 2-8-4's and had 63" drivers and 28"x30" cylinders, same as the 1922 2-8-2 that led to the 2-8-4, and typical of the drag era. They had a high calculated tractive effort but that came from a formula; the A-1's big firebox and boiler were intended to produce greater horsepower so B&A could move trains faster in the mountains of Western Massachusetts, and they did just that.

The later 2-8-4's were designed for speed on level track and the NKP S-2 has 69" drivers and 25"x34" cylinders which can move freight faster.

Interestingly when B&A parent NYC wanted greater speed on level track they used 4-8-2's.

Phil Mulligan

The two books I have show 69,400 lbs. T.E. and 81,400 including the booster for the B&A A-1a. Engine weight was 389,000 lbs. Tender weight, fully loaded was 201,900 lbs. Maximum Drawbar HP of the nearly identical Lima prototype A-1 measured on the B&A was 3420 HP.
The NKP S-2 engine and tender weights were 440,800 lbs. and 285,270 lbs. The S-2's average Drawbar HP above 30 mph was 3915 HP. I haven't read what their maximum DBHP was.

as a question what would be more efficient and economical for today's environment for mainline trips? the early berks or the modern berks? If an early berk was still in existence.

I want your opinion on that.

That's actually almost incredibly easy.

No early Berk would be at all suited to modern operation without significant modification. You have all the rail-pounding augment of a 2-8-2, and all the excessive fuel consumption at part load of a 4-8-4. An articulated trailing truck that will not 'push' correctly in reverse, where much of an excursion engine's time might be involved.

Meanwhile, any modern Berk qualifies, as the L&N Emmas did, as a 4-8-4 built a little shorter to fit turntable clearances.

Even a 4-8-2 like early Mohawk 2933 at MOT is a poor candidate for an excursion engine. Whereas 3001 in Elkhart is one of the most promising projects yet left 'unsupported'...

Perhaps the best example is that of a slightly larger first-generation dog turned into a more modern silk purse: T&P 610. This was built as one of the very first Super-Power 2-10-4s, an early Berk with an additional driving axle. Not until this received a significant and 'knowing' rebuilding in the mid-Thirties did it become a suitable road engine. (But oh brother! what a good engine it then became!)

The situation wasn't limited just to Berks. The ATSF 3751 class of 'heavy Mountains' were slow and augment-prone as built. It took not one, but two rebuildings to get 3751 in the shape she currently is, and in the detail design of those two campaigns you have much of the answer of what early eight-coupleds would have needed.