Interesting - this looks like military equipment and tank transport trailers. Did the Colorado National Guard do it as a training exercise or was it private equipment? Wikipedia shows an Abrams tank as weighing 54-65 tons depending on version, so without trucks these engines would be in that range. Lighter on the trailer but now you need one or two big cranes on each end of the move.
>Good old 1203, she always did want to get up and go! We had like thirteen cars behind her and she was chomping at the bit on the Sumpter Valley.
Taylor's memory is correct, we through every car we had with weight and the 1203 pulled it. AS Sumpter Valley's grades and curves aren't anywhere close to the Loop, even with a heavy train we couldn't duplicate the trailing friction due to grades and curves. On the test runs, the 1203 was left at full throttle using the train air to hold the train to the speed limit all the way to the Sumpter yard limits. The only time I got it to slip was stopping on the heavy grade just before the Sumpter depot, and then trying to start the train before the brakes had completely released.
> ... the 1203 wants to run smaller trains really fast... So they traded it for the 9 because it is slow and has lots of power.
As overhauled, the 1203 was completely capable of pulling full tonnage at around 10 mph up a grade, probably would have done 8 mph all day long at full throttle. If it could only run a small train too fast then there is either a problem with how the control system is functioning (remember everything was changed to repower it with the Alco 6-251) or there was a problem in the cab.
I found a serial number for DSNG No 7 "Big Al" (but not the No 9) Assuming that the 9 was a similar spec or was upgraded to a similar spec, it might have a pair of Cummins NT-855L4 engines which would be rated at 600 hp. Even if newer/bigger Cummins engines were installed (helpful due to the derating for altitude), the electrical system and traction motors would only be about 600 hp - about the same as 1203.
A company's website claims they are rebuilding a GE 80 ton for the Loop, and the information and pictures they have suggest it isn't the one from Colorado Public Service. So is there ANOTHER GE 80 ton diesel on its way to the Loop besides the ones that are on the property? Maybe they have the missing trucks and are converting them to narrow gauge for CHS?
While the friction of the trailing cars due to the grade and curvature doesn't change with the type of engine, few people understand how a steam locomotive or a diesel locomotive develops its tractive effort. If Shay 9 is rated at 36,150 pounds of tractive effort, in THEORY it would be good for around 236 trailing tons up the grade, maybe a train of 8 or 9 former White Pass parlor cars? The issue becomes at what speed the engine can run the train while developing the neede tractive effort. It doesn't do any good to come up the hill at 5 mph when the schedule requires 10 mph.
Diesel-electrics develop tractive effort in inverse proportion to speed, and in direct proportion to horsepower, subject to adhesion, mechanical and thermal limitations. So one 600 hp diesel-electric is pretty much the same as another 600 hp diesel-electric, and they will develop about the same tractive effort at 10 mph to maintain the schedule.
My best guess is that the Loop will be somewhat disappointed in their new "bigger" diesels, definitely uphill and possibly even downhill. Steamies shouldn't be allowed to play with diesels.
