The reference for locomotives and railcars


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Soo Line classes H-3 and H-21 to H-23
United States | 1911 | 31 produced
H-23 No. 2719 in September 2007 at Two Harbors, Montana
H-23 No. 2719 in September 2007 at Two Harbors, Montana
Pete Markham

In 1911 Soo Line and its Wisconsin Central subsidiary began manufacturing a series of Pacifics ranging from the H-3 to the H-23 of 1923. It started with eleven H-3s and ten H-21s, which differed almost only in the boilers of different sizes. Like their successors, they had cylinders measuring 25 by 26 inches and 75-inch wheels. Initial boiler pressure of 185 psi was soon increased to 200 psi. Three H-3s and one H-21 still exist today.

In 1914 four examples of the H-22 class were added, which already had a slightly smaller boiler with a pressure of 200 psi. It was not until 1923 that six examples of the H-23 class followed, which essentially corresponded to the H-22. These were retired by 1959. Numbers 2718 and 2719 still exist today. 2718 is now in Green Bay, Wisconsin and 2719 was serviceable for a long time until the boiler deadline of 2013.

Axle config4-6-2 (Pacific) 
Gauge4 ft 8 1/2 in (Standard gauge)
Dimensions and Weights
Length82 ft 6 3/4 in
Length loco46 ft 7 1/2 in
Wheelbase34 ft 7 in
Fixed wheelbase13 ft 6 in
Total wheelbase66 ft 2 in71 ft 1 in
Service weight277,570 lbs259,000 lbs264,000 lbs281,080 lbs
Adhesive weight171,960 lbs158,500 lbs163,000 lbs172,400 lbs
Total weight420,570 lbs402,000 lbs407,200 lbs496,080 lbs
Axle load61,610 lbs55,000 lbs57,400 lbs59,000 lbs
Water capacity7,500 us gal12,000 us gal
Fuel capacity24,000 lbs (coal)35,000 lbs (coal)
Power sourcesteam
Estimated power1,850 hp (1,380 kW)1,875 hp (1,398 kW)1,975 hp (1,473 kW)2,000 hp (1,491 kW)
Optimal speed35 mph34 mph35 mph
Starting effort34,071 lbf36,833 lbf
Power Plant
Driver diameter75 in
Boiler pressure185 psi200 psi
Expansion typesimple
Cylinderstwo, 25 x 26 in
Grate area52.8 sq ft
Firebox area207.4 sq ft207 sq ft
Tube heating area3,184.6 sq ft3,331.6 sq ft3,184.6 sq ft3,172 sq ft
Evaporative heating area3,392 sq ft3,539 sq ft3,392 sq ft3,379 sq ft
Superheater area805 sq ft736 sq ft840 sq ft
Total heating area4,197 sq ft4,344 sq ft4,128 sq ft4,219 sq ft
Calculated Values
steam locomotive
last changed: 10/2022

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