plastic gear

例句：

1. 1. The new car has a plastic gear that makes it easy to change the speed.
   这款新车有一个塑料齿轮，使换挡变得很容易。
2. 2. The engineer used plastic gears to make the machine more efficient.
   工程师使用塑料齿轮使机器更加高效。
3. 3.The plastic gears on the conveyor belt are designed to prevent jams and keep the machinery running smoothly.
   输送带上的塑料齿轮设计用来防止卡住并保持机械平稳运行。