The reference for locomotives and railcars


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Nippon Tetsudō Bbt2/5
Japanese Government Railways class 6600
Japan | 1897 | 24 produced
Railway and Locomotive Engineering, January 1901

Baldwin delivered 24 Atlantic locomotives to the Nippon Tetsudo in 1897, which were to remain the only Japanese engines with this wheel arrangement. In terms of design, it was a typical American Atlantic, but it had been reduced in size for the Cape gauge of 3 ft 6 in and the significantly smaller loading gauge. Thanks to the trailing axle and the space-saving bar frame, it was possible to arrange the firebox completely behind the coupled axles and to make it very wide, which was otherwise difficult with steam locomotives with a smaller gauge. Also typically American were the large driver's cab and the high-mounted running boards. Due to the inside Stephenson valve gear of American design, the locomotives looked very tidy, since only the connecting and coupling rods could be seen from the outside.

In the initially private railway they were designated as Bbt2/5 with the operating numbers 506 to 529 and were used on today's Joban line on the east coast. The available coal was not of high quality, but thanks to the large grate area, the boiler could still produce a lot of steam. After nationalization in 1906, the locomotives were given the numbers 6600 to 6623 by the JNR. Since only two of the five axles on Atlantic locomotives were powered, they were soon replaced by newer superheated steam locomotives with greater adhesive weight. All 24 machines were quickly scrapped in April and May 1925.

Axle config4-4-2 (Atlantic) 
Gauge3 ft 6 in (Cape gauge)
Dimensions and Weights
Length53 ft 5 1/2 in
Wheelbase22 ft 6 in
Fixed wheelbase6 ft
Total wheelbase45 ft 11 1/2 in
Service weight100,980 lbs
Adhesive weight52,000 lbs
Total weight160,980 lbs
Axle load30,464 lbs
Water capacity3,000 us gal
Fuel capacity12,000 lbs (coal)
Power sourcesteam
Estimated power800 hp (597 kW)
Optimal speed33 mph
Starting effort15,387 lbf
Power Plant
Driver diameter56 in
Boiler pressure180 psi
Expansion typesimple
Cylinderstwo, 16 x 22 in
Grate area30 sq ft
Firebox area98.2 sq ft
Tube heating area1,461.9 sq ft
Evaporative heating area1,560 sq ft
Total heating area1,560 sq ft
Calculated Values
steam locomotive
last changed: 03/2022

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