rail head calipers

例句：

1. 1.The engineer used a rail head caliper to measure the length of the track.
   工程师使用轨道头卡尺测量轨道的长度。
2. 2.The construction crew used the rail head caliper to check the alignment of the tracks.
   施工队使用轨道头卡尺检查轨道的对齐情况。
3. 3. The inspector used the rail head caliper to ensure that the rails were properly installed.
   检查员使用轨道头卡尺确保铁轨安装正确。