A helping hand. The smoke from the K-27 road engine up ahead is still fresh in the air as C-18 class Consolidation #315 charges past, providing mid-train power to help lift the heavy Rio Grande Southern Freight up a desert grade in Western Colorado.
Colorado's narrow gauge railroads such as the Denver & Rio Grande Western and the Rio Grande Southern often placed helper locomotives in the middle of the consist, rather than double-head. This was typically done to avoid overloading the structures of some of the longer bridges that existed on these lines. The practice became more common in the early decades of the 20th century, as larger and more powerful locomotives such as the K-28, K-36 and K-37 became available. Note that this locomotive carries the flying Rio Grande herald of the D&RGW, despite the fact that it is operating for the Rio Grande Southern. This is because the "Southern" was owned by the Denver & Rio Grande Western for most of its existence, and much of the RGS Power consisted of locomotives that were sold, leased or loaned from the parent corporation. In the case of leased or loaned power, the locomotives generally retained their original lettering and there are plenty of historic photos which document this practice.
This photo was taken during a 2017 re-creation that was organized by the Friends of the Cumbres & Toltec Scenic Railroad and operated on the line between Chama, NM and Antonito, CO.