Tunnel driving cylinder position checking system - uses gyroscopic compass enclosed in protective housing with connecting line to atmosphere

摘要

The tunnel driving system using a tunnelling shield or cutting cylinder (2) behind which tunnel lining sleeves are installed, uses a gyro compass (4) mounted inside the cylinder. This is used to check the direction of travel of the cylinder. Since this must be operated at atmospheric pressure, the compass is mounted inside a protective housing (5) with a line connecting it to atmosphere. The compass may be used with an auxiliary compass (9) to measure angles.