Japanese National Railways 4-6-0 Locomotives in Japan


Class Details by Steve Llanso of Sweat House Media

Class 8700 - superheated (Locobase 3807)

Data from Hiroshi Takagi, both from his website ([link]) and personal communication August 2000. His indispensable assistance is gratefully acknowledged.

Note that when the 8700s (Locobase 3806) were superheated, they received larger pistons as well, which increased tractive effort. Note too how many fewer tubes the boiler had when space was made for the large superheater flues.


Class 8800 -- retubed (Locobase 3809)

Data from Hiroshi Takagi, both from his website ([link]) and personal communication August 2000. His indispensable assistance is gratefully acknowledged.

When the 8800s were retubed, they mirrored what seems to have been standard Japanese practice by emphasizing the flue area at the expense of tube cross-section. Also, notice the big increase in the weights. One wonders if this was a very successful design or did the weight growth reflect a lack of control of detail design.


Class 8850 - refitted (Locobase 3811)

Data from Hiroshi Takagi, both from his website ([link]) and personal communication August 2000. His indispensable assistance is gratefully acknowledged.

Retubed 8850s (Locobase 3810) with more, smaller flues and fewer tubes.

Principal Dimensions by Steve Llanso of Middle Run Media
Class8700 - superheated8800 -- retubed8850 - refitted
Locobase ID3807 3809 3811
RailroadJapanese National Railways (JNR)Japanese National Railways (JNR)Japanese National Railways (JNR)
CountryJapanJapanJapan
Whyte4-6-04-6-04-6-0
Number in Class
Road Numbers8850
Gauge3'6"3'6"3'6"
Number Built
Builder
Year
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.48 / 4.1113.75 / 4.1912.01 / 3.66
Engine Wheelbase (ft / m)25.50 / 7.77 / 7.88
Ratio of driving wheelbase to overall engine wheelbase 0.54
Overall Wheelbase (engine & tender) (ft / m)47.46 / 14.47 / 14.60
Axle Loading (Maximum Weight per Axle) (lbs / kg)27,844 / 12,63029,520 / 13,39029,674 / 13,460
Weight on Drivers (lbs / kg)83,533 / 37,89088,538 / 40,16089,023 / 40,380
Engine Weight (lbs / kg)113,362 / 51,420118,785 / 53,880126,854 / 57,540
Tender Loaded Weight (lbs / kg) / 29,450
Total Engine and Tender Weight (lbs / kg) / 86,990
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)46 / 2349 / 24.5049 / 24.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)63 / 160063 / 160063 / 1600
Boiler Pressure (psi / kPa)184.20 / 1270185 / 1280185.60 / 1280
High Pressure Cylinders (dia x stroke) (in / mm)18.5" x 24.02" / 470x61018.5" x 24" / 470x61018.5" x 24.02" / 470x610
Tractive Effort (lbs / kg)20,431 / 9267.3620,502 / 9299.5620,586 / 9337.66
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.09 4.32 4.32
Heating Ability
Tubes (number - dia) (in / mm)79 - 2.008" / 5166 - 2" / 5166 - 2.244" / 57
Flues (number - dia) (in / mm)22 - 5.236" / 13319 - 5.25" / 13319 - 5" / 127
Flue/Tube length (ft / m)13.48 / 4.1115 / 4.5714.99 / 4.57
Firebox Area (sq ft / m2)125.89 / 11.70126.97 / 11.80123.52 / 11.48
Grate Area (sq ft / m2)20.01 / 1.8620.01 / 1.8619.48 / 1.81
Evaporative Heating Surface (sq ft / m2)1081 / 100.501099 / 102.101096 / 101.82
Superheating Surface (sq ft / m2)363 / 33.70368 / 34.19368 / 34.18
Combined Heating Surface (sq ft / m2)1444 / 134.201467 / 136.291464 / 136
Evaporative Heating Surface/Cylinder Volume144.65147.19146.66
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation368637023615
Same as above plus superheater percentage460746274519
Same as above but substitute firebox area for grate area28,98629,36228,657
Power L112,88213,12713,106
Power MT1019.95980.60973.69

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