Firebox heating surface included 29.6 sq ft of arch tubes. Data from diagram. The first 192 delivered used Baker valve gear, the remainder moved steam with the Young gear, which had two rods, two links and allowed cutoffs to be set as high as 90% of stroke.
This class was the backbone of freight work on the Chicago & North Western. Many later saw a major increase in superheater area; see Locobase 8383.
Delivered over a period of 10 years, the class remained in widespread service well into the 1950s.
The Omaha division actually was part of the Chicago & NorthWestern Railway, but it ordered and serviced its own locomotives. Even so, most of its classes were very similar to NorthWestern engines. This set of Js were virtually identical to the C&NW Js (Locobase 6306) , says Larry Bohn, author of the website members.lsol.net/mollyandmic/c393.htm. The only differences were the number of digits in the number and a missing horizontal cross-bar in the Omaha Js' cab windows.
Firebox heating surface included 29.6 sq ft of arch tubes.
Most of the class was rebuilt in 1937-1938 and redesignated Class Ja.
These were classic USRA Heavy Mikado engines with a slight difference in tube count. Schenectady delivered four in April 1919, but Richmond's six followed almost 2 years later in January 1921.
According to http://members.lsol.net/mollyandmick/C437.htm (last accessed 1 June 2006), these were modernized USRA Heavy Mikados with Delta cast-steel trailing trucks, Type E superheater, and an exhaust steam injector. One remarkable feature of this class was the single diameter of tube used in the boiler - all 232 tubes measured 3 1/2" each.
432-435 were fitted with thermic syphons that added 84 sq ft (7.8 sq m) to the firebox heating surface in addition to the 14.3 sq ft (1.33 sq m) that remained of the arch tubes. This raised total direct heating surface from 307 sq ft to the 368.3 sq ft (28.5 sq m) shown in the specs. Steam entered the cylinders through 14" (356 mm) piston valves.
These Mikes saw steam out on the Chicago & North Western. Firebox heating surface includes 27 sq ft (2.5 sq m) of arch tubes.
This renovation of the original J (Locobase 6306) design saw a substantial increase in its superheater area as well as an increase in driver diameter. A few surrendered their arch tubes in favor of circulators. The 51 sq ft of the latter device increased the firebox heating surface to 281 sq ft. Subsidiary St Paul, Minneapolis & Omaha rebuilt many of its J-class locomotives (at least 23 of the 32, as far as Locobase can tell). These had exhaust-steam injectors.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Chicago & North Western (C&NW)||Chicago, St Paul, Minneapolis & Omaha (C&NW)||Chicago, St Paul, Minneapolis & Omaha (C&NW)||Chicago, St Paul, Minneapolis & Omaha (C&NW)||Chicago & North Western (C&NW)|
|Number in Class||310||32||10||8||30|
|Builder||Alco-Schenectady||Alco-Schenectady||Alco||Alco-Schenectady||C & NW|
|Valve Gear||various||Baker||Walschaert||Baker or Young||various|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||16.80 / 5.12||16.80 / 5.12||16.75 / 5.11||16.75 / 5.11||16.80 / 5.12|
|Engine Wheelbase (ft / m)||37.60 / 11.46||37.60 / 11.46||36.08 / 11||37.59 / 11.46||37.25 / 11.35|
|Ratio of driving wheelbase to overall engine wheebase||0.45||0.45||0.46||0.45||0.45|
|Overall Wheelbase (engine & tender) (ft / m)||72.30 / 22.04||72.30 / 22.04||71.62 / 21.83||72.30 / 22.04||69.56 / 21.20|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)|
|Weight on Drivers (lbs / kg)||229,500 / 104,100||229,500 / 104,100||239,000 / 108,409||249,000 / 112,945||237,000 / 107,502|
|Engine Weight (lbs / kg)||304,500 / 138,119||304,500 / 138,119||320,000 / 145,150||333,000 / 151,046||319,000 / 144,696|
|Tender Loaded Weight (lbs / kg)||175,400 / 79,560||175,400 / 79,560||183,800 / 83,370||188,900 / 85,684||184,000 / 83,461|
|Total Engine and Tender Weight (lbs / kg)||479,900 / 217,679||479,900 / 217,679||503,800 / 228,520||521,900 / 236,730||503,000 / 228,157|
|Tender Water Capacity (gals / ML)||8275 / 31.34||8275 / 31.34||10,000 / 37.88||10,000 / 37.88||9500 / 35.98|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||16 / 14.50||16 / 14.50||16 / 14.50||16 / 14.50||14 / 12.70|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||96 / 48||96 / 48||100 / 50||104 / 52||99 / 49.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||62 / 1575||62 / 1575||63 / 1600||63 / 1600||64 / 1626|
|Boiler Pressure (psi / kPa)||185 / 12.80||185 / 12.80||200 / 13.80||200 / 13.80||200 / 13.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||27" x 32" / 686x813||27" x 32" / 686x813||27" x 32" / 686x813||27" x 32" / 686x813||27" x 32" / 686x813|
|Tractive Effort (lbs / kg)||59,167 / 26837.73||59,167 / 26837.73||62,949 / 28553.22||62,949 / 28553.22||61,965 / 28106.88|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||3.88||3.88||3.80||3.96||3.82|
|Firebox Area (sq ft / m2)||259.60 / 24.13||259.60 / 24.13||307 / 28.53||368.30 / 34.22||259.60 / 24.13|
|Grate Area (sq ft / m2)||63.10 / 5.86||63 / 5.86||70.30 / 6.53||70.30 / 6.53||63.10 / 5.86|
|Evaporative Heating Surface (sq ft / m2)||4154 / 386.06||4154 / 386.06||4283 / 398.05||4020 / 373.61||3795 / 352.70|
|Superheating Surface (sq ft / m2)||890 / 82.71||890 / 82.71||993 / 92.29||2000 / 185.87||1112 / 103.35|
|Combined Heating Surface (sq ft / m2)||5044 / 468.77||5044 / 468.77||5276 / 490.34||6020 / 559.48||4907 / 456.05|
|Evaporative Heating Surface/Cylinder Volume||195.89||195.89||201.97||189.57||178.96|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||11,674||11,655||14,060||14,060||12,620|
|Same as above plus superheater percentage||13,775||13,753||16,731||18,700||15,523|
|Same as above but substitute firebox area for grate area||56,671||56,671||73,066||97,968||63,862|