It is a disc or collar with an irregularly shaped edge, which operates in contact with a rod or lever, and causes it to oscillate, or to move to and fro.是什么意思_It is a disc or collar with an irregularly shaped edge, which operates in contact with a rod or lever, and causes it to oscillate, or to move to and fro.在線翻譯_英語_讀音_用法_例句