This is reponse to Mke Trent's request.
The D&RGW class K-27s are the Holy Grail of fans of the Rio Grande narrow gauge. These engines were used on most of the narrow gauge lines, except for the mileage through the Black Canyon of the Gunnison, where bridge restrictions kept them from regular service. Starting around 1928, they also saw a lot of use on the Rio Grande Southern. While they wre supposed to run on 55lb track, they ran on a lot of 40 lb rail on the RGS and the Santa Fe line.
These engines ran approximately half a century. From their long operating history, it is obvious that the Grande was never quite happy with their performance. They were delivered in 1903 as Vaulclain compounds. This was a good idea- recycle steam from a high pressure cylinder to a low pressure cylinder. The problem all owners of locomotives of this design faced is that the crosshead had two piston valves. The high pressure cylinder pressed harder than the low pressure cylinder, causing the piston packing to wear out quickly. Old Fred Jukes photos of the Oregon Shortline engines (the UP was a big buyer of Vauclains) show the front of the engine and a huge cloud of steam, thus obscuring precious visibility. Around 1908 this entire class received simple engine blocks, a major refitting. This class ran another 20 years with this change. After the arrival of the class K-28s the operating department took another look at these engines and refitted 454, 456, 458 and 461 with piston valves, but kept the Stephenson valve gear. This was also not entirely satisfactory, and a different engine block with outboard valves and Walschearts valve gear was installed on 452,453,454,455,459,462,463 and 464. Most of these engines also received superheater manifolds at this time. For reasons unknown the 450,451,457 and 460 never received the third modification. It is known that there was a big drop-off in mining business on the narrow gauge after 1925 and the company was already making decisions about the eventual closing of their narrow gauge system.
The 463 and the 464 were the last of this class to operate. 463 was purchased in 1955 by Gene Autry for his movie set in California. It never oeprated there. The movie set burned down about the time the demand for Autry's B-westerns was waning . He donated the engine to Antonito in 1971 or 2. In the 1990s funding was gathered and work started on repairing the engine. It required a complete rebuild. The result of the work, organized by Jack Campbell and John Bush was arguably one of the finest historic renovations of a locomotive ever.
How did it run? This was a very enjoyable engine to run. The engine was comfortable to operate, with controls placed where an engineman did not neeed to reach far to operate. It had a very reponsive throttle and tracked very well, though not quite as good as 473 and 476. It had a short wheelbase and a big overhang in the back-like the 480s, and would nose around in curves but with none of the violence the 480s would display. It also, like the 470s, could go relatively fast and feel safe. It had no backhead insulation so the cab was hot. The lifting injectors always worked fine. The negative-and it was a big one-was the engine steamed poorly. It served the engineeer and fireman well to clean the fire themselves- and as thoroughly as possible, especially in front. Earl and I agreed that if the perfect notch in the cutoff and the perfect notch in the throttle were found it would run up Cumbres without running out of steam. An RGS fireman and a couple of D&RGW employees told me it never steamed well. (454 was also siad to be a poor steamer) Earl told me something very interesting. Most of the class received new smoke-boxes at some point in the 1920s, usually after the third cylinder rebuild. Apparently the stack on 463 was not lined up with the exhaust nozzle below- and that would indeed affect its ability to steam. Like the 470s and all of the smaller engines, the K-27s had Master Mechanic front end skirting . I never like this system, though it could be easily adjusted to change draft and (hopefully) steam better.
On the road the engine did swing gently from side to side. Apparently the whole class did this, earning the moniker "mudhen" Yeah, there are other explanations but I stand by this one. The 463 had no apparent problems double-heading with larger engines.
This summer I was fortunate to ride the 464 at Huckleberry, and their beautiful restoration certainly rivals the one John and jJck did on 463 in 1994. I loved running the 463 and never quite got over how fortunate I was to do so. Let's hope it someday will run again over Cumbres.