KiHa 66 series

The KiHa 66 series was a medium-capacity commuter diesel multiple unit operated initially by the Japanese National Railways and later the Kyushu Railway Company from March 1975 to June 2021, often used on express services.
==History==
The KiHa 66 series was developed in the early 1970s prior to the opening of Hakata Station on the San'yō Shinkansen. The cars were intended for use for "Shinkansen Relay"-type services in the Chikuhō and Kitakyushu areas, and entered service on 10 March 1975 to fulfill that role. The cars were initially located at Nōgata Depot, mainly operating on the Sasaguri and Chikuhō Main Lines on Handa and Hida express services. At the time the cars were manufactured, JNR's financial situation was starting to get dire, and as such only 15 sets were manufactured. The cars's axle loads were also notably heavier than most other cars; these made it difficult for these cars to operate on other lines and new lines could not be created to allow these to run there, also due to JNR's financial situation.
With the privatization of JNR, ownership of all cars was assumed by JR Kyushu. Even with the introduction of the KiHa 200 series cars on the lines, the KiHa 66 series cars remained in use, particularly along non-electrified lines around the Kitakyushu Region; the trains were then partially refurbished for wanman operation in 2000, although some equipment such as the fare boxes and ticketing machines were not installed. Electrification works on the Chikuhō and Sasaguri Lines were completed in 2001, and as such the KiHa 66 series cars were no longer needed on those lines; they were thus transferred to Nagasaki Depot and fare boxes and ticketing machines were installed, completing the wanman operation conversions.
In 2013, all cars were transferred to Sasebo Depot and were used mainly on the Sasebo, Ōmura and Nagasaki Main Lines. With the introduction of the revised timetable in 2015, set 66 4 was retired from service and scrapped in 2016; the remaining cars were then refurbished. The introduction of the YC1 series with the 2020 timetable revision caused further withdrawals and retirements. As of mid-June 2021, 8 sets remained in service; all were retired on 30 June 2021. No KiHa 66 series cars have been preserved.
==Design==
The KiHa 66 series featured a squarish design with the iconic dual headlight setup of diesel railcars produced around that time. The cars were painted in a variety of liveries: the original express livery (Cream No.4 "Wheat" base coat with Vermillion No.4 "Golden Red" accents), a blue Sea Side Liner livery or an orange Huis Ten Bosch livery. The cars were originally painted slightly differently, with the basic Cream No.4 "wheat" base coat with Red No. 4 "Scarlet" accents.
===Liveries===
KiHa 66-6 2021.jpg|Sea Side Liner blue
KiHa 67-12 2021.jpg|Huis Ten Bosch orange
==Specifications==
Construction was of steel. These featured the same basic design as most contemporary JNR diesel railcars, but featured a slightly raised cab to strengthen frontal crash protection against level crossing incidents. In modern days the cars were mainly considered to be suburban diesel locomotives, despite the fact that the cars featured performance statistics which far surpass that of their contemporaries, such as the KiHa 58 series cars. Railroad magazines classified the KiHa 66 series cars as a "general purpose diesel railcar" for that purpose, but that nomenclature failed to catch on as cars of that type were not being continuously manufactured.
The KiHa 66 series cars were initially fitted with the DML30HSH prime mover, a horizontal banked V12 producing 434 HP (440 PS); these were the most powerful prime movers JNR had at the time. Despite this, the engines were difficult to maintain and had poor fuel efficiency, so these were swapped out for DMF13HZA prime movers starting 1993. These prime movers produced an equivalent amount of power (414 HP/420 PS) while being easier to maintain. Power was initially transmitted through a manual hydraulic transmission; this was later changed to a 2-speed automatic hydraulic transmission manufactured by Niigata Converter.
Category:Diesel trainsets
Category:JR Group trains
Category:Fuji Heavy Industries locomotives
Category:Niigata Tekkō locomotives
Category:Passenger locomotives
Category:Japanese locomotives