master track pin

例句：

1. 1.The engineer used a master track pin to fix the broken rails.
   工程师用一个主轨道钉来固定断裂的铁轨。
2. 2.The construction crew had to use master track pins to support the weight of the new bridge.
   施工队伍不得不使用主轨道钉来支撑新桥的重量。
3. 3. The train was able to run smoothly thanks to the master track pins installed in the tracks.
   由于在轨道上安装的主轨道钉，火车能够平稳地运行。