locomotive underframe

例句：

1. 1. The engineer carefully inspected the locomotive underframe before starting the engine.
   工程师在启动引擎前仔细检查了机车底座。
2. 2.The train was equipped with a new locomotive underframe to improve its performance.
   这列火车配备了新的机车底座，以提高其性能。
3. 3. The underframe of the locomotive is crucial for maintaining the stability of the train.
   机车的底座对于保持列车的稳定性至关重要。