空转轮

例句：

1. 1. The old machine had a rusty empty wheel.
   这台旧机器有一个生锈的空转轮。
2. 2.The car's engine was so loud that it sounded like an empty wheel spinning.
   汽车发动机的声音太响了，听起来就像一个空转轮在旋转。
3. 3. The engineer carefully removed the empty wheel from the gearbox.
   工程师小心翼翼地从齿轮箱中取出了空转轮。