Osaka Metro 20 series

The Osaka Metro 20 series is a Japanese city commuter electric multiple unit operated by the Osaka Municipal Transport Bureau and later Osaka Metro from December 1984 to March 2024. 
==History==
The 20 series trains were introduced based on a study conducted by the Osaka Municipal Transport Bureau regarding the use of variable frequency drives in train locomotives; this study dated back to 1979. The first set, 2601, was manufactured in March 1984 and underwent test running after; it entered revenue service on 24 December 1984, becoming the first Japanese subway train using a variable frequency drive. Seven sets were introduced on the Chūō Line, with a further nine being built for use on the Tanimachi Line starting 1989. 24 series sets were later introduced to supplement these sets.
Refurbishment works for the trains began in 2004 and were completed in 2006; that same year, the Tanimachi Line trains were transferred to the Chūō Line and repainted as such. The first set, 2601, was retired in 2014 and scrapped with a number of special final run events held to commemmorate its withdrawal. As of 2022 the remaining 15 sets remain in service, although they are expected to be replaced by 400 series trains from 2023; the 23 series trains on the other hand are expected to be redeployed on other lines. The sets were withdrawn from service on 20 March 2024.
==Design==
The 20 series sets feature a conventional front end with two top-mounted headlights. These were styled in a similar fashion to the 10 series sets on the Midōsuji Line. Many of the train's elements were later incorporated in the later New 20 series trains.
==Specifications==
Construction is of aluminum. The sets used early-specification Hitachi GTO drives which produce a droning noise which steps up in pitch; these have been largely replaced by Hitachi IGBT drives which produces a high-pitch whine which steps up in pitch. 
The 20 series trains were the first trains on the Osaka Municipal Subway to feature an electronic horn.
Category:Osaka Metro trains
Category:Electric trainsets
Category:Osaka Municipal Subway trains
Category:Hitachi locomotives
Category:Kawasaki locomotives
Category:Kinki Sharyo locomotives
Category:Tokyu Car locomotives