locomotive tractive force

例句：

1. 1. The train's locomotive is responsible for propelling the train forward.
   火车头的驱动力使火车前进。
2. 2. The locomotives are essential components of the railway system.
   火车头是铁路系统的重要组成部分。
3. 3. The engineer had to replace the locomotive's gearbox due to wear and tear.
   工程师不得不更换火车头的齿轮箱，因为磨损严重。