Denver & Rio Grande Western class K-28
originally class 140
When 20 years had passed since the later class K-27 was purchased from Baldwin, the D&RG purchased ten additional locomotives from ALCO-Schenectady. These were also Mikados with an outside frame, in which the cylinders, driving and coupling rods, as well as the valve gear were located on the outside. They were initially listed as class 140 and were renamed into the now better-known class K-28 after the D&RGW was founded.
They were the first D&RG locomotives to have a superheater from the beginning. The fact that the class designation indicates only a slightly higher tractive power compared to the K-27 is due to the fact that the drivers now measured 44 instead of 40 inches. However, this, combined with better mass balancing, ensured higher speeds, which is why the crews nicknamed them the “Sports Models”.
During World War II, seven were drafted by the military and taken to Alaska, where they served on the White Pass & Yukon. These were scrapped after the war, while the other three remained in use with the D&RGW until the fifties. They then came to the Durango & Silverton, where they have been pulling tourist trains ever since. The 473 is still in use today, having been converted to oil firing in 2022.
Technical data
General
- Built
- 1923
- Manufacturers
- ALCO
- Wheel arrangement
- 2-8-2 (Mikado)
- Gauge
- 914 mm (Three feet)
Dimensions and weights
- Wheelbase
- 8.79 m
- Total wheelbase
- 16.31 m
- Service mass
- 70.8 t
- Adhesion mass
- 51.5 t
- Total mass
- 115.4 t
- Rigid wheelbase
- 3.73 m
- Axle load
- 12.9 t
- Water capacity
- 18,927 l
- Fuel capacity
- 7.3 t (coal)
Boiler
- Grate area
- 2.796 m²
- Firebox surface
- 9.476 m²
- Tube heating surface
- 138.611 m²
- Evaporative heating surface
- 148.088 m²
- Superheater surface
- 39.205 m²
- Total heating surface
- 187.3 m²
Power plant
- Driver diameter
- 1,118 mm
- Boiler pressure
- 13.8 bar
- Expansion type
- simple expansion
- Cylinders
- two, 457 x 559 mm
Power
- Power source
- steam
- Estimated power
- 839 kW (1,141 PS)
- Starting effort
- 122.5 kN
Calculated values
- Factor of adhesion
- 1 : 4.12
- Optimal speed
- 42 km/h
- Power-to-weight ratio
- 11.9 kW/t
- Heating Surface Equivalent
- 273.9 m²
- Cylinder volume/HSE
- 1 : 669.94
- Adhesive weight/Total
- 1 : 1.37
- Tractive force/Heating surface
- 1 : 13.66
- Grate area/Heating surface
- 1 : 66.99
- Firebox/Tube surface
- 1 : 14.63
- Total/Superheater
- 1 : 3.78