The Denver & Rio Grande K-27 class was a group of narrow-gauge 2-8-2 locomotives that marked a major increase in power over the railroad’s earlier Consolidations.
The class used outside frames, placing the main frames beyond the driving wheels instead of between them.
That arrangement helped accommodate larger running gear within the restrictions of three-foot gauge.
The K-27s were originally built as compound locomotives, expanding steam through more than one cylinder stage.
The Rio Grande later rebuilt the class into simpler arrangements that were easier to maintain in regular service.
The locomotives earned the nickname “Mudhens,” though the exact origin of the nickname is less important than the operating identity it gained among railroaders and enthusiasts.
K-27s worked freight and branch-line service throughout the surviving narrow-gauge system.
As the more powerful K-28, K-36, and K-37 classes entered service, the K-27s shifted toward secondary work.
Only a very small number survived preservation, including D&RGW No. 463.
For TransitSatellite, the K-27 page should explain the engineering transition. It is not simply a smaller K-36: its compound origins, proportions, and early outside-frame design place it in a different development stage.