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The reference for locomotives and railcars

Denver & Rio Grande Western class K-28

originally class 140

United States 1923 10 produced
No. 472 in July 1938 in Salida, Colorado L.S. Brown / collection Taylor Rush

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
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