E231 series

The E231 series is a Japanese commuter electric multiple unit operated in a number of different forms by the East Japan Railway Company since March 2000. It is one of a few main types of rolling stock used on urban commuter services on JR East, with another being the E233 sets, as well as some long-distance services. It is most famously known as the main rolling stock on the Yamanote Line, a major loop line in the Tokyo region, from 2000 to 2020.
==History==
The E231 series was designed in 1998 to replace various city commuter trains like 103, 201, 205 and 301 series sets and outer-suburban commuter trains like the 113 and 115 series. The first set entered service on 13 March 2000.
A total of 2,736 cars were built, with the majority still in service based at various depots around Japan. Occasionally, six-doored cars are inserted into the sets to allow for more passengers to board the train during busy periods. These were originally used on the Yamanote Line, but with the addition of platform screen doors on most of the stations to standardize door spacing, these six-doored cars were removed and replaced by new cars with irregularly-spaced doors to fulfill the same purpose.
Of note is that the first set delivered, E231-900 series set B901, was actually originally classified as a 209-950 series set; that set entered service on 27 March 1999. The set was reclassified as E231-900 series set B901 in June 2000 with the manufacture of the full-production cars. B901 was removed from service on the Chūō-Sōbu Line on 9 July 2020 and subsequently transferred to the Musashino Line, reformed as an 8-car set and renumbered MU1; the two cars removed from the set were scrapped in December 2020.
The sets were entirely phased out of service on the Yamanote Line on 20 January 2020, with YaTe506 (now A506) carrying a special headmark.
==Design==
The E231 series uses a modern design with an unpainted stainless steel body very much like most JR East commuter trains; the sets are based on the 209 series so some design language does carry over. Each set has a different color scheme to indicate which area the sets serve. The sets have a wide variety of different body styles based on the different variations of the set. The basic designs of the sets was designed by industrial designer Kenji Ekuan.
===Variations===
;Livery variations
Operating area	Front end	Body side
 	 	
Chūō-Sōbu Line	
{| border="0" cellspacing="0" width="100"	
 	 	
;Cab design variations
There are four cab design variations of the E231 series, with each cab design variation being used on the role the sets are used on.
E231-0 B3 Akihabara 2017.jpg|Mid-distance commuter set B3 in May 2017
E231-900 B901 Higashi-Koganei 2015.jpg|Prototype mid-distance commuter set B901 (now MU1) in January 2015
E231-1000 S20 Tōkaidō 2017.jpg|Outer-suburban set S20 in February 2017
E231-800 K5 Minami-Gyōtoku 2010.jpg|Narrow-body set K5 in November 2010
E231-500 A507 Akihabara 2017.jpg|City commuter set A507 in July 2017
E231-500 525 Akihabara 2018.jpg|City commuter set YaTe525 (now A525) in February 2018
==Specifications==
Construction is of stainless steel. Cars are 20 meters long, 2.95 meters wide and 3.98 meters high. Traction motors are powered by three-level insulated gate bipolar transistors supplied by Mitsubishi or two-level IGBT drives supplied by Hitachi and Mitsubishi which are only used on various refurbished sets. 
The Mitsubishi drives fitted on the E231-0, E231-500, E231-800 and E231-900 series sets make a distinctive, wind-like noise when the train accelerates from idle; the later-build E231-1000 series sets use early-spec Hitachi drives which make a shrill noise which later dies down but rises in pitch again; refurbished sets use two-level Mitsubishi drives which make a hissing noise or later-spec two-level Hitachi drives which make a high-pitched wooshing noise.
There are even other variations of the two-level Hitachi drives which do not have the abrupt pitch shifts.
The E231 series sets are one of a few sets which are the blueprints for successive trains developed by JR East; others include the E233 and 209 series sets.
==References==
*Wikipedia.org
Category:JR Group trains
Category:Electric trainsets
Category:Tokyu Car locomotives
Category:Kawasaki locomotives