change gear train

例句：

1. 1.The engineer changed the gear train to make the car go faster.
   工程师换档使汽车更快行驶。
2. 2. The old car had a worn-out gear train that needed replacing.
   旧车有一个磨损的变速装置需要更换。
3. 3. The train's gear train was damaged during the accident.
   火车在事故中损坏了变速装置。