DandRGW K 37

Denver & Rio Grande Western K-37s are 2-8-2, Mikado type, narrow gauge steam locomotives. They were originally built by Baldwin as part of an order for thirty standard gauge 2-8-0, Consolidation type, locomotives, class 190, in 1902. They were renumbered into class C-41 (meaning 41,000 lbs of tractive effort) during the railroad's reorganization in 1924 and were converted to three foot gauge in 1928-30 at the railroad's Burnham Shops in Denver, CO with many new parts including new frames and smaller drivers. They were then renumbered into class K-37.

The locomotives are of outside-frame design, with the driving wheels placed between the two chassis frames which support the boiler, but with the cylinders, driving rods, counterweights and valve gear on the outside. This general arrangement is shared with the earlier K-27, K-28 and K-36 Mikado engines.

The locos worked out of Salida, Colorado to Gunnison, Colorado and up the Crested Butte Branch as well as the Monarch Branch. The locos also worked out of Alamosa, Colorado to Antonito over Cumbres Pass to Chama and on to Durango and the Farmington Branch. Like the K-36s the locos were not permitted West of Gunnison or on the Silverton branch. However, the Silverton branch has since been upgraded the track and line to handle K-36s and K-37s. 3 K-37s, 493, 491, and 499, were equipped with steam heat and signal lines so they can haul passenger trains like the San Juan Express and Shavano.

Of the eight preserved K-37s, only #497 has been operational, both on the Durango and Silverton Narrow Gauge Railroad and on the Cumbres and Toltec Scenic Railroad but it is now awaiting a major overhaul. However, in 2014, engine #491 went under restoration at the Colorado Railroad Museum. On Saturday, September 13, 2014 the #491 operated for the public for the first time at the Colorado Railroad Museum (a ticketed "roll out" was hosted on August 29, 2014), providing the motive power for the annual Thomas the Tank Engine event. On May 4, 2016 the D&SNG, in cooperation with the Colorado Railroad Museum, transported the #493 to Durango after resting in Silverton for almost 20 years for a joint evaluation project.

Although the K-37s are actually about 2% lighter than the K-36s, they were erroneously thought to be much harder on track. Although the D&S originally owned four of the K-37s, they found that the longer engines were too hard on their track and they didn't handle the Animas Canyon section of the route as well as they would have hoped, so they traded #497 to the C&TS for K-36 #482 and #499 to Royal Gorge Park in Canon City for #486.