train air signal valve

例句：

1. 1.The train air signal valve is used tocontrol the flow of air during the train's operation.
   训练用的气信号阀用于控制火车运行过程中空气的流动。
2. 2. Thetrain air signal valve is essential for maintainingthe safety of the train system.
   训练用的气信号阀对于维护火车系统的安全至关重要。
3. 3.The train air signal valve is designed toprevent the train from running out of airwhile in operation.
   训练用的气信号阀设计用来防止火车在运行中因空气不足而停止。