721 series

The 721 series is a Japanese suburban electric multiple unit operated by the Hokkaido Railway Company since November 1988.
==History==
The 721 series sets were constructed from 1988 to 2003 as a new type of train that could cope with the increased demand for transport in the suburbs of Sapporo, along with competing with other transportation systems like high-speed bus services and cars on highways. As the older 711 series sets were deemed to be unsuitable for the aforementioned purpose, the 721 series sets were developed, with an all-new design both externally and internally.
The first sets entered service on 3 November 1988 with the introduction of the dual-track systems on the Hakodate Main Line and Chitose Line. A total of 135 cars were produced from 1988 to 2003 in three- or six-car formations; the sets were produced by Hitachi, Kawasaki Heavy Industries and Tokyu Car Corporation, although they were also available in knockdown kit form from JR Hokkaido's Naebo Works. All 135 cars are in service and are all based at Sapporo Depot.
==Design==
The 721 series sets adopted a new body style that forms the basic design language for later suburban-style trains that were to be built for JR Hokkaido. The sets have two pairs of headlights; a pair of top-mounted headlights and a pair of body-mounted headlights. Some sets, such as F3102 as shown above, have had their body-mounted headlights switched out to high-intensity discharge fixtures. The sets have unpainted stainless steel bodies with green accents, a color scheme which would be carried over to the later 733 and 735 series sets.
==Specifications==
Construction is of stainless steel. End cars are 21.67 meters long, 2.95 meters wide and 4.05 meters high. The first five batches of the 721 series sets use a thyristor drive system, while the later 721-4000 series sets use gate turn-off thyristor variable frequency drives produced by Toshiba or Mitsubishi; the Toshiba drives produce a distinctive wailing sound while the Mitsubishi drives produce a droning sound that steps up in pitch.
The 721-5000 series sets have insulated gate bipolar transistor variable frequency drives produced by Hitachi which produce a distinctive shrill shriek. Some 721-3000 series sets have been refurbished with later-specification Hitachi IGBT drives that produce a hissing sound.
Some sets are equipped with U-seat cars.
==Trivia==
*The "F" in the sets' fleet number designation (i.e. F3222) apparently stands for Fast according to some sources.
==References==
*Wikipedia.org
Category:JR Group trains
Category:Electric trainsets
Category:Hitachi locomotives
Category:Kawasaki locomotives
Category:Tokyu Car locomotives
Category:Locomotives
Category:Narrow-gauge
Category:Narrow-gauge locomotives
Category:3 foot 6 inch gauge
Category:Japanese locomotives
Category:Japan
Category:Naebo Works locomotives