Changing C425 to C625?

[philnrunt]

I have 5 HO Atlas Alco 4 axle Centurys, and I would really like to convert them to six axle units to reflect my lightweight branchline track and have a unique loco. Has anyone tried this with an Atlas loco, and how did it work out?
I have no clue as to what truck sideframes are available, and I would definitely like to keep the gearing they currently have.
Any tips, hints ,or actual experience will be greatly appreciated.
Thanks, guys.

[jkeaton]

If you have lightweight branchline track, are you sure you want six-axle units? While I know there are a few prototypes for six axle units on light track - the RSC-2 and GMD-1 come to mind - usually branchline track implies tighter curves too, and the prototype tended to avoid using six-axle units on sharply curved track, preferring to go to more, lighter four axle units. There were lightweight versions of the GP7, GP9 and RS11 available from the factory for just this purpose.

Frankly, I'd just replace your C425 heavy haulers with something more prototypically lightweight, like an RS-1, switcher, lightweight GP9, or even a GE 70-tonner, depending on your interests. Leave those lovely Atlas mechanisms alone!

Besides, there never was a C625.

Jim

[jrbernier]

Phil,

The C425 was a high HP unit for it's time. Alco never offered a 6 axle variant. By the time of the C425, most 6 axle units were not built to spread axle loading, but were used to provide 'unit reduction'. They just weighed 50% more than the 4 axle units! Most prototype rail lines with 90-100 lb rail will hold them. The GB&W ran C424 - C430 class engines on 90 lb jointed rail with a 45 mph speed limit. The only real limitation was old bridges. One of the few 'modern' engines designed for light rail lines were the 10 SDL39 class engines the Milw Road bought for light rail branches. These were 2,300 hp units on special 'export' trucks. They were shorter than a standard GP35 unit.
The Kato RSC2 was a good example of a low axle loading engine, and would be perfect for a branch line or shortline with light rail/bridges. Also, many of the 600 hp switchers could be ordered with a 50,000 lb axle loading option. EMD offered the SD7 and SD9 with a 50,000 lb axle loading option(150 tons rather than 180+ tons for a standard SD). So, the P2K SD7 or SD9 also could be a good light rail engine. The Milw Road had a fleet of lightweight SD's for branches. Most only had the rear fuel tank and no D/B equipment. I hope this info helps....

Jim Bernier

[philnrunt]

Jim and ...Jim- Thanks for the feedback, but I feel like I didn't make my point clear.
This conversion would not be only for the light rail, I realized I should not have emphasized that point, but this would represent an in-shop conversion by my RR to get more traction for the ore drags they will be hauling.
It would be more along the lines of a RR building their own model, like SF's CF-7 rebuild than trying to actually be prototypically correct and true to ALCo history.
I have some SD-9's, and they worked fine until I fell in love with AlCos. They hold an honored place on the shelf of fame. It's right next to the shelf of shame, where I keep all of my bizarre attempts at motive power.
But leaving those lovely mech's alone, well, that also has it's merits!