JNR Class DE50

The JNR Class DE50 is a diesel-hydraulic locomotive operated by the Japanese National Railways from February 1971 to May 1986.
==History==
The DE50 was designed as a locomotive which could replace the DD51, intended to be a heavy switcher locomotive. The locomotive was intended to be significantly more powerful than the DD51 while retaining the same light weight and being as easy to maintain as the DD51s.
One locomotive was manufactured by Hitachi at their Kasado factory in July 1970; numbered DE50 1, the locomotive was numbered as such as it was intended to be a mass-production prototype. Assigned to Inazawa Rolling Stock Depot, DE50 1 was used to pull freight trains on a trial basis before it was introduced into service in February 1971. The locomotive was transferred to Okayama Rolling Stock Depot on 20 November 1971, where it was used on the Hakubi Line.
Although DE50 1 was of an ambitious design, the rapid electrification of many of the JNR's lines, an oil crisis and JNR's worsening financial situation meant that any plans for full production of the DE50 were called off, leading to DE50 1 being the only locomotive built; any diesel locomotives to be produced for the JNR would be DD51s. Despite this, DE50 1 would remain in use on the Hakubi Line where its hydrodynamic brakes were tested; a malfunction with the locomotive put it out of service, whereupon it was stored at Okayama Rolling Stock Depot and officially withdrawn on 26 May 1986, having not operated for more than ten years. DE50 1 would be stored at Okayama Station for a number of years before it was moved to the Tsuyama roundhouse in 2011 for preservation. DE50 1 remains at the roundhouse, now known as the Tsuyama Railroad Educational Museum, where it is preserved alongside a number of other diesel locomotives and railcars.
==Design==
DE50 1 features a steeplecab-like design, giving it an appearance similar to that of a switcher locomotive; this design was chosen to help the locomotive reduce its weight by reducing its axle load. Unlike the similar-looking DD51 and DD13 locomotives, DE50 1 features a long hooded design due to it only having one engine as opposed to two. The driver's cab is notably off-center; it was designed as such to allow for switching and short turnaround operations.
==Specifications==
DE50 1 is fitted with a single V16 prime mover, designated the DMP81Z. Total power output is about 2,000 PS (1,471 kW). DE50 1 uses a DW7 hydraulic transmission; the transmission works similarly to a Voith turbo transmission. Cooling of the engine and other components is done through a pair of fans forcing air into the components via cooling shafts.
==Preservation==
The following Class DE50 locomotives have been preserved:
Number	Manufacturer	Date manufactured	Date retired	Location 	Notes
DE50 1	Hitachi 	21 July 1970 	26 May 1986 	Tsuyama Railroad Educational Museum, Okayama, Japan	Displayed in roundhouse; only DE50 built
Category:JR Group trains
Category:C-B locomotives
Category:Diesel locomotives
Category:Diesel-hydraulic locomotives
Category:Hitachi locomotives
Category:Japanese locomotives