idle pulley

例句：

1. 1. The idle pulley is a common part of many machines.
   空转滑轮是许多机器的常见部件。
2. 2. The idle pulley was responsible for the machine's slow speed.
   空转滑轮导致机器速度缓慢。
3. 3. The idle pulley had to be replaced after several years of use.
   经过几年的使用，空转滑轮不得不更换。