JR East Japan announced that brake parts used on more than 500 cars on the Yamanote Line and other lines were not processed at the time of manufacture to maintain strength. JR says that there are no safety problems immediately and that the condition will be checked through regular maintenance.
According to JR East Japan, it was found that the two types of parts used in the brakes of some of the trains owned by the company were not originally processed to maintain strength, which is done during manufacturing.
A total of 2 vehicles manufactured after 2015, including the E235 series on the Yamanote Line and Yokosuka Line, were discovered in September when they were testing the parts.
The parts are manufactured by an external manufacturer commissioned by JR Japan East, and the process of heating the steel material of the parts to remove hydrogen has not been carried out, and the cause is unknown.
After the discovery, a sample was inspected, and it was said that the strength standards were met at this time, so there was no safety problem immediately, and the condition was confirmed by regular maintenance.
JR East Japan said, "We apologize for the concern" and will continue to investigate the cause.