Osaka Metro 70 series

The Osaka Metro 70 series is a Japanese linear-motored city commuter electric multiple unit operated by the Osaka Municipal Transport Bureau and later Osaka Metro since March 1990 on the Nagahori Tsurumi-ryokuchi Line.
==History==
The 70 series was a completely new design that was conceived in 1990. The first set, pre-production set 7101, was delivered to the Osaka Municipal Subway in March 1990 and entered service on 20 March 1990. The remaining sets were delivered over the coming years. The sets have been progressively refurbished starting from 2011. When the Osaka Municipal Transport Bureau decided to hand over ownership of the Osaka Municipal Subway in 2018, ownership of the sets was transferred to Osaka Metro. All sets are in service and are based at Tsurumi Depot.
==Design==
The 70 series uses a fairly modern design with a body made of an extruded aluminum alloy. All sets have painted white aluminum bodies with green accents indicating the line the sets serve on. The prototype set had no green accents when originally manufactured; those were added at a later date. Some refurbished sets have pink accents in addition to the green accents.
==Specifications==
Construction is of an extruded aluminum alloy. End cars are 16.25 meters long, 2.49 meters wide and 3.145 meters high.
The sets use Hitachi gate turn-off thyristor inverters which produce a low droning noise, while refurbished sets use insulated gate bipolar transistor variable frequency drives also produced by Hitachi which produce a sharp hissing noise. 
The use of linear motors in the sets gave the sets an extremely unique droning noise once the sets reached high enough a speed; this characteristic is only found on linear-motored trainsets. In addition to the odd-sounding motors, the linear motor system does provide some benefits, such as allowing for smaller cars and tunnels; however, this disallows the 70 series sets from performing through-running to and from other lines due to technological incompatibilities, in addition to most other lines having technology that only works with rotary-motored trains.
While it is technically possible for rotary-motored trains to operate on the Nagahori Tsurumi-ryokuchi Line, where the 70 series sets see service, a different loading gauge and smaller tunnels prevent such occurrences.
==References==
*Wikipedia.org
Category:Osaka Metro trains
Category:Electric trainsets
Category:Osaka Municipal Subway trains
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