D&RGW 2-8-8-2 locomotives

[Gandy Dancer]

I have three D&RGW references that have the classification for the 2-8-8-2 standard gauge as: -96, L-107, L-109, L-131, and L-132.  

I can find no reference of an L-125.  Does anyone know what this might be?
http://cgi.ebay.com/United-Scale-Models-Rare-Rio-Grande-D-RGW-L-125-2-8-8-2_W0QQitemZ110173210757QQihZ001QQcategoryZ484QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

Did at one time they rework the classification system or just call some of them by different classes at different times like they did for the L-95 to L-96? 

[Sperandeo]

Hello "Gandy,"

The D&RGW's simple-articulated 2-8-8-2s in the 3600 series came in two batches of 10, the L-125s from Brooks in 1927 and the L-127s from Schenectady in 1930. The numbers in D&RGW road classes indicated tractive effort in thousands of pounds. At some point the boiler pressure of these engines was increased, giving them greater tractive effort. The L-125s became L-131s, and the L-127s became L-132s. By the way, when the L-125s were delivered in 1927, they were the largest steam locomotives in the world. They may have had that title only briefly, but it was theirs for a time.

So long,

Andy

[Sperandeo]

This topic aroused my curiosity and I did a little more digging. I think I was wrong to say that the boiler pressure of the L-125 and L-127engines was raised. It appears to have always been 240psi.

The change resulting in the changed road class seems to have been in the valve gear cutoff. These engines were built with their valve gear set up for limited cutoff, an economy measure that stopped admitting steam to the cylinders at 60 percent of the stroke. This used less steam per power stroke while allowing the steam to work expansively, i.e., pushing the piston as it expanded. At some time that I still haven't found in the sources I've consulted, the cutoff was increased to perhaps 80 percent or more. This may have been done as early as 1930, i.e., shortly after delivery of the L-127s.

Increasing the cutoff has the effect of raising the cylinder steam pressure to a higher percentage of the boiler pressure, so the tractive effort equation yields a higher result.

Incidentally, both the L-131s and the L-132s were rated for 131,800 pounds t.e. under those classifications, so the difference in the last digit of the classification is soley to distinguish the two groups. The 1930 engines, the L-127/132 classes, did have internal improvements to their boilers, fireboxes, and steam passages that should have increased their horsepower, but would not have affected their tractive effort.

I'm still curious to know if I'm correct about what was changed to increase the tractive effort of these locomotives, and when it was done.

So long,

Andy

[R. T. POTEET]

. . . . . . . . . . I'm still curious to know if I'm correct about what was changed to increase the tractive effort of these locomotives, and when it was done . . . . . . . . . . .

So long,

Andy

I always thought that the best way to increase tractive effort was to add traction tires.

Just a little levity - this is a serious subject and I am not making light of it; I drove over three hundred and fifty miles today to a fund raising BBQ for our church camp at Prescott, Ariz and I'm just a little bit on the tuckered-out side!