Denver & Rio Grande Western class K-27
originally class 125
United States 1903 15 produced
The K-27 class was the last compound locomotive built for the D&RGW. The “K” stood for “Mikado” and the number for starting tractive effort of 27,000 pounds. They had four compound cylinders and was of the Vauclain type, but rebuilt into a simple two-cylinder just four years after delivery. As with other narrow-gauge locomotives of the D&RGW, the axles were in an outside frame. The nickname “Mudhen” came about because in the original configuration they often derailed. Most K-27 were scrapped in the fifties and the last two built still exist today. No. 463 runs on the Cumbres & Toltec Scenic Railroad and No. 464 is owned by the Huckleberry Railroad and last ran in 2019.
Technical data
General
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Built | 1903 | 1907-1911 | 1924 |
| Manufacturers | Baldwin | D&RGW | |
| Wheel arrangement | 2-8-2 (Mikado) | ||
| Gauge | 914 mm (Three feet) | ||
Dimensions and weights
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Wheelbase | 7.47 m | ||
| Total wheelbase | 15.56 m | ||
| Service mass | 56.9 t | 62.1 t | 63.6 t |
| Adhesion mass | 45.4 t | 47.3 t | 49.1 t |
| Total mass | 89.6 t | 99.9 t | 101.4 t |
| Rigid wheelbase | 3.48 m | ||
| Axle load | 11.9 t | 12.5 t | 12.7 t |
| Water capacity | 13,249 l | 15,520 l | |
| Fuel capacity | 7.7 t (coal) | ||
Boiler
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Grate area | 2.806 m² | 2.803 m² | |
| Firebox surface | 9.848 m² | 10.498 m² | |
| Tube heating surface | 188.315 m² | 131.272 m² | |
| Evaporative heating surface | 198.162 m² | 141.77 m² | |
| Total heating surface | 198.2 m² | 179.6 m² | |
| Superheater surface | 37.812 m² | ||
Power plant
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Driver diameter | 1,016 mm | ||
| Boiler pressure | 13.8 bar | ||
| Expansion type | compound | simple expansion | |
| Cylinders | four, HP: 330 x 559 mm and LP: 559 x 559 mm | two, 432 x 559 mm | |
Power
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Power source | steam | ||
| Estimated power | 671 kW (912 PS) | 820 kW (1,115 PS) | |
| Starting effort | 104.2 kN | 120.2 kN | |
| Starting effort simple | 125.0 kN | ||
Calculated values
| Property | as built | rebuilt simple | superheated |
|---|---|---|---|
| Factor of adhesion | 1 : 4.27 | 1 : 3.86 | 1 : 4.01 |
| Optimal speed | 39 km/h | 34 km/h | 42 km/h |
| Power-to-weight ratio | 11.8 kW/t | 10.8 kW/t | 12.9 kW/t |
| Heating Surface Equivalent | 247.4 m² | 269.9 m² | |
| Cylinder volume/HSE | 1 : 940.76 | 1 : 661.51 | 1 : 606.41 |
| Adhesive weight/Total | 1 : 1.26 | 1 : 1.31 | 1 : 1.30 |
| Tractive force/Heating surface | 1 : 10.98 | 1 : 12.67 | 1 : 13.98 |
| Grate area/Heating surface | 1 : 70.62 | 1 : 64.07 | |
| Firebox/Tube surface | 1 : 19.12 | 1 : 12.50 | |
| Total/Superheater | 1 : 3.75 | ||
