JNR Class DB10

The JNR Class DB10 was a type of diesel-mechanical locomotive designed by the Ministry of Railways, the predecessor of the Japanese National Railways (JNR). 
== Background ==
In response to the global recession after World War I, railway management would required to rationalize. As part of this effort, the conversion of tasks such as shunting from steam locomotives to diesel was planned in order to save on labor and fuel costs. Therefore, this model was produced as the first domestically produced diesel locomotive.
== Structure ==
The engine used in this locomotive is a diesel engine (inline 4-cylinder, 50 ps/1,000 rpm) manufactured by Ikegai Seisakusho or Kobe Steel. The body and assembly were handled by Kawasaki Sharyo, Nippon Sharyo, and Hitachi. This was the first domestically produced diesel locomotive by the Ministry of Railways and required many improvements before practical use.
The power transmission system adopted a 4-speed mechanical transmission. Power is transmitted from the transmission to the reverser under the floor, then outputted through a sprocket and driven by a single axle through a roller chain inside the frame. Additionally, another axle is linked through rods on the outside of the wheels.
The braking system uses drum brakes instead of the common shoe-on-rail method. A brake drum is attached to one side of the underfloor reverser shaft and is operated through linkage from a manual brake lever.
== Manufacturing ==
In 1932, eight cars were manufactured. The exact manufacturing period is unknown, but it is believed to be around March to April of the same year. According to the locomotive allocation table of each railway bureau as of April 30th of the same year, DB10 1 and DB10 2 were newly allocated to Takatori locomotive depot (however, DB10 2 was being modified at Kawasaki Sharyo at the end of the month). DB10 3 was allocated to Kōzu locomotive depot, DB104 to Takasaki locomotive depot, DB10 5 and DB10 6 to Sendai locomotive depot, DB10 7 to Hamamatsu locomotive depot, and DB10 8 to Inazawa locomotive depot.
== Service ==
Afterwards, they were dispersed and placed in units of 1-2 cars to each railway bureau, where they were used for light shunting operations at stations and factories. However, in 1938, DB10 5 was taken out of service at the Kushiro Engine Depot Akkeshi Stabling Point, and due to fuel control, it was mostly taken out of operation after 1943. During the war, except for DB10 1 working as a shunter at Wakamatsu Inspection Depot, DB10 5 working as a shunter at Hakodate Engine Depot, DB10 6 working as a shunter at Morioka Works Machinery Division, and DB10 8 working as a shunter at Fukui Engine Depot, all the others were taken out of service. It should be noted that according to the locomotive allocation table of the Sapporo Railway Bureau as of April 1, 1948, DB10 5 was classified as a first-class out-of-service locomotive at Hakodate Engine Depot. Furthermore, DB10 3 and DB10 4 were scrapped at Oyama Engine Depot in September 1948; they were the last of the eight locomotive to be withdrawn.
== Retirement and disposition ==
Regarding the two units (DB10 1, DB10 7) of the Moji Railway Bureau, after the war, they were converted and used as freight car movers at Moji Port Station. One of these units was scrapped early on, but the remaining unit was used until the late 1980s when the Kitakyushu Materials Center, where it was stationed, was closed. After the closure of the center, the remaining locomotive was scrapped. The distinctive large riveted structure of the cab and bonnet, which characterized this type, was gradually replaced, resulting in the loss of its original appearance. The number plates were also not preserved 5, so in its final days, it appeared only as a freight car mover, making it difficult for those who were unaware of the circumstances to recognize it as the original DB10 type.
It was also used for moving vehicles within the premises of the Maibara Engine Depot. The bonnet was removed and replaced with seven tanks, and it became a non-steam locomotive driven by compressed air to power the wheels. It had a speed of 4-5 km/h and a towing capacity of about 230 tons. It had the designation MN01 and the number plate MAB1.
== Gallery ==
File:20180710163036729756 e82c511ed2fd10764429a8c7ecbee1ad.jpg
Category:Japanese locomotives
Category:Diesel locomotives
Category:Diesel-mechanical locomotives
Category:Hitachi locomotives
Category:Kawasaki locomotives
Category:Nippon Sharyo locomotives
Category:Locomotives
Category:Built in 1932
Category:Scrapped locomotives
Category:Scrapped diesel locomotives
Category:B locomotives