Chicago, St. Paul, Minneapolis, & Omaha Ry., Class "I-1" 4-6-0 #317

photo taken near Sarona, Wisconsin Circa 1950

This Early I-1 varies substanially from the later ones even to a casual observer. Slanted Cylinders with no outside "Monkey Motion" or valve gear indicates that the valves are operated by "inside valve gear" (Stephenson valve gear) which is mounted between the frames. The 4 bar crosshead guides are reminicient of the 1890's rather than the 20th. century, and the cab window arrangement is not the standard of later I-1's and K-1's.

Incidentally, Don't try to make any sense out of Omaha's numbering and classification system. There was none. I-1's were 10-wheelers but I-2's were Pacifics, K-1's were 10 wheelers but K-2's were pacifics. #106 was an I-1, but #107 was a K-1. #363 was an I-1 but #364 was a G-3 4-4-2. Class E-3's were originally 4-4-0's but were later 4-6-2's (The heaviest ever built, world wide). Classes seemed to be designated by cylinder size rather than wheel arrangement and numbers of retired engines were re-assigned to new engines regardless of class. Three class K-1, 4-6-0's built at the same time and bearing consecutive Schenectady construction numbers (50123-9 of 7/11) were numbered 108,112, & 230. In later years classification followed the same system used by C.& N.W.

Series...........................#302-353 (Stephenson valve gear.)

Cylinders, Dia. & Stroke=........ 21" x 26" ~ Overall Height =............................. 15'-5,1/4"

Valve, (Piston)..............................12" ~ Width over Cylinders =.......................9'-8,3/4"

Valve Gear= ....................Stephenson ~ Rigid wheel base = ............................14'-10"

Driving wheel Diameter =...................63" ~ Engine wheel base = .........................25'-10"

Boiler Pressure,.........................200 lb. ~ Eng length over buffer plates=........ .39'-3,3/8"

Grate Area =...........................46 sq. ft. ~ Wheel base, Eng/Tend.=.....................59'-1"

Firebox, L. / W. =........102,1/8" X 65,1/4". ~ Length Eng. & Tender =................69'-7,1/2"

Length over tube sheets...................15'-0" ~ Wt. on lead truck .......................41,000 lb.

Tubes, Dia. & No.=2".......................160 ~ Wt. on Drivers =.......................138,000 lb.

Flues, Dia. & No.=5,3/8"....................28. ~ Wt. of total Engine =..................179,000* lb.

Htg. Surface, Tubes...............1248.6 sq. ft. ~ Tender Wt., Loaded.................. 143,300 lb.

Htg. Surface, flues..................587.3 sq. ft. ~ Wt. eng. & Tender=...................322,300 lb.

Htg. Surface, Arch tubes =...........24.2 sq. ft. ~ Wt. of Engine, light =................157,200 lb.

Evaporative Htg. Surface, total =.2012.1 sq. ft. ~ Tender Wt., light...................... 64,300 lb.

Superheater surface,(Type "A").... 493.0 sq. ft. ~ Tender capacity, Water = ............7,500 gal.

Combined Htg. Surface =..........2505.1 sq. ft. ~ Tender capacity, Coal =..................15 tons.

Boiler Dia. 1st. ring =.............. 66,3/8" O.D. ~ Tractive force =.........................30,940 lb.

Height of boiler center = ...............9'-1,3/4" ~ Factor of Adhesion =......................... 4.46

Stoker=........................................none ~ Wt on Drivers/ engine wt.=...............77.09%

Air Pump =... 1, Cr. Cpd. 8,1/2" Westinghouse ~ Ratio, Htg. Sur. to Grate area =........... 43.74

Minimum Curve =.. 19 Degrees or 303 ft. radius ~ Ratio TF per lb. boiler Pressure=..........154.7

*Note: C&NW specifications for class R-1 ten-wheelers which were nearly the same as the I-1's state that the engines equipped with Stephenson Valve gear were not quite 10 tons lighter than those built later with Walschaert gear. Omaha specs. do not make this distinction but it probably existed in the I-1's also.

Built by Alco-Schenectady,9/02. C.N. 25426
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