minor sprocket

例句：

1. 1. The car needs a minor sprocket to keep it running smoothly.
   这辆车需要一个小齿轮来让它运行顺畅。
2. 2.The engineer replaced the minor sprocket with a new one.
   工程师用一个新的小齿轮替换了旧的。
3. 3.The machine's performance was significantly improved after the minor sprocket was replaced.
   更换了小齿轮后，机器的性能有了显著提升。