History of the Prototype


As the Nineteenth Century came to a close, the Denver & Rio Grande’s narrow gauge lines in Colorado and New Mexico had settled into the role of feed lines to the railroad’s standard gauge lines. The narrow gauge hauled ores, coal, lumber, oil, farm products, and general merchandise that were an important source of revenue.

The railroad had begun to replace much of the rolling stock with new and larger cars as the smaller freight cars strained under increasing traffic demands. Locomotives, however, were another matter. The D&RG had not purchased any new narrow gauge locomotives since 1887. The older, smaller engines still in service struggled to manhandle the freight and passenger traffic over the line's 4% grades and 24 degree curves. It was common for trains to require three or four of the Class 400 2-8-0s to move just 100 tons of freight.


In 1901, the D&RG mechanical department sought a remedy for this problem. They solicited design specifications for a locomotive of a size and capacity to handle at least twice the tonnage of the 2-8-0s then in use. Early in 1903, the railroad selected Baldwin Design Specification W4213 and ordered 15 locomotives. They would be assigned road numbers 450 to 464. These locomotives would be unlike anything yet built for American narrow gauge. They were outside frame 2-8-2s with Vauclain compound cylinders and sloped back tenders for better visibility. Compound cylinders were in vogue at this time, as they were supposed to provide smoother running and more fuel efficiency.


The new locomotives were designated as Class 125. In preparation for their arrival, the Denver & Rio Grande began

laying heavier rail on many of its lines. While they were being broken in after delivery in April, 1903, it was observed that the new engines had a tendency to “waddle” as they moved down the track. They were soon given the nickname “Mudhen,” after the Coot duck, which had a similar gait.


The Class 125's compound cylinders and small tenders soon proved inadequate for the demands of mountain railroading. At times, as many as half of them were in the shops for repairs. In 1907, the railroad converted the first locomotive, number 458, to a simple engine by replacing the 17-inch by 22-inch cylinders with D-slide valve steam chests. This experiment was a tremendous success, and by January, 1912, all of the remaining compounds (except number 456) had been changed to simple engines. Additional improvements were made over the next three years, including the addition of a second air pump, flange lubricators, electric headlights, generators, and new smokestacks. In 1918, larger rectangular tender tanks were fabricated in the railroad’s Burnham shops. All the while, the Mudhens’ operating territory continued to expand as further track improvements were made on many of the narrow gauge branches.


Starting in 1923, the Denver and Rio Grande began to apply piston valves and Walschert valve gear to the Mudhens as they rotated into the shops for repairs and maintenance. As they emerged, they were given the now familiar designation of K-27 Class. Over the next few years, most of the Mudhens were upgraded to the new cylinders and valve gear as well as new cross compound air pumps and boiler tube pilots. Between 1927 and 1928, superheating was added to the K-27’s specifications. Many trainmen with experience on both the narrow and standard gauge lines considered the superheated Mudhens to be the finest riding and running engines on the entire Denver & Rio Grande system.


Like many businesses of the day, the Denver & Rio Grande Western narrow gauge was hit very hard by the Great Depression in 1929. Many K-27s experienced long periods of inactivity. In 1939, the four Mudhens that had not received piston valves and Walschert valve gear were cut up for scrap. Also, the D&RG traded number 455 to the Rio Grande Southern for ditcher 030. That left the D&RG with a total of 10 remaining K-27s. In December of 1941, numbers 458 and 459 were sold to the Nacionales de Mexico, dropping the roster to eight Mudhens.


World War II brought a flurry of activity to the narrow gauge. The K-27s were put to hard use, with all of the remaining eight locomotives in service almost daily. When the war ended in 1945, business on the narrow gauge began to spiral downward again, and the end was in sight for many locomotives on the system, including the K-27s. One by one, the Mudhens succumbed to the scrapper’s torch until only two remained. Fortunately, they are both with us today. Number 464 operates regularly on the Huckleberry Railroad in Flint, Michigan, and Number 463 is on the Cumbres and Toltec Railroad in her native Colorado and New Mexico.