Class 923 Shinkansen

The Class 923 Shinkansen is a non-revenue earning high-speed electric multiple unit operated by the Central Japan Railway Company since October 2000 and the West Japan Railway Company since March 2005. It is the latest generation of the Doctor Yellow high-speed track inspection trains.
==History==
The first Class 923 set, set T4 (designated the 923-0 series), was delivered in October 2000. It was meant to replace Class 922 set T2; T2 was retired in 2001. 
A second Class 923 set, set T5 (designated the 923-3000 series), was delivered in March 2005. It was meant to replace Class 922 set T3; T3 was retired the same year.
The sets carry out their track, electric and signal inspections at full speed (270 km/h, 170 mph). Operation schedules of the Doctor Yellow sets are not made public, often exciting railfans when sighted; a highly popular Shinkansen model, significant amounts of merchandise has been manufactured on the class. It is stated that seeing a Doctor Yellow train brings good luck.
With the retirement of the 700 Series Shinkansen sets the Class 923 is based on, it has often been stated that the Class 923s are to be withdrawn from service; JR Central and West have confirmed that both sets will continue to run "for the time being", although JR Central plans to install measurement equipment on the N700S Series Shinkansen to allow for higher accuracy readings.
T4 is stationed at Ōi Rolling Stock Depot while T5 is stationed at Hakata Shinkansen Depot; despite this, T5 is often stationed at Ōi, with JR Central performing periodic inspections on T4 and T5. Monthly inspections are carried out in Tokyo while repairs are carried out at Hamamatsu Works.
T4 is slated to be withdrawn in January 2025, while T5 is slated to be withdrawn "after 2027"; inspection duties are planned to be carried out by N700S Series Shinkansen sets with onboard inspection equipment in future. After withdrawal, one of T4's lead cars will be preserved at the SCMaglev and Railway Park.
==Design==
As mentioned above, the Class 923 Shinkansen is based on the 700 Series Shinkansen, and as such, looks identical to it with the exception of the prominent square cavity in the middle of the noses of the end cars.
==Specifications==
The end cars are 27.35 meters long and the intermediate cars are 25 meters long. Both sets use 3-level IGBT variable frequency drives with PWM converters manufactured by Toshiba, which gives them a rather melodic whine when they accelerate from idle.
The sets have a very noticeable black square cavity in their noses which holds a surveillance camera. Car 1 is used for inspecting signals and electrical equipment. Car 2 is used solely for inspecting electrical equipment. Car 3 has an observation dome with yet another surveillance camera. Car 4 is used for inspecting the track with sensors lining the side of the car. Car 5 is a multipurpose test car with another observation dome and doubles as resting quarters. Car 6 is used for inspecting electrical equipment and doubles as a meeting room. Car 7 is practically identical to Car 6; being used to inspect electrical equipment, but doubles as resting quarters.
==References==
*Wikipedia.org
==Gallery==
File:Shinkansen Class 923 Maibara.jpg|Class 923 set T4 at Maibara Station.
Category:JR Group trains
Category:Electric trainsets
Category:Hitachi locomotives
Category:Nippon Sharyo locomotives
Category:Built in 2000