Toho Tenax Co. Ltd. has partnered with Kawasaki Heavy Industries Ltd. to develop a carbon fiber reinforced plastic, or CFRP, leaf spring that can be mass-produced for railcar trucks. The leaf spring was initially developed in 2013 and is already used in Kawasaki's new-generation railcar truck, the efWING.

Toho Tenax will help establish an integrated system encompassing everything from the carbon fiber's original yarn to the actual CFRP leaf springs. The new mass-production system will enable the efWING to be marketed on a global scale.