noun
Mechanical term for a central rotating rod or spindle that transmits motion or supports parts. 心棒 is the core shaft inside a machine or device.
この機械の心棒が曲がってしまった。
The shaft of this machine has bent.
旋盤の心棒に材料を取り付ける。
Attach the material to the lathe's mandrel.
noun
central figure; core member; linchpin
Figurative use for a person who is the central pillar or driving force of a group or organization.
彼はチームの心棒として活躍している。
He is active as the central figure of the team.
あの人が会社の心棒だ。
That person is the linchpin of the company.
Compound of 心 (しん, 'core, heart') and 棒 (ぼう, 'rod, stick'). The literal meaning is 'core rod', which developed into the mechanical sense of a central shaft and later the figurative sense of a central person.