| 摘要 |
<p>Tunnelling, heading etc. shield is fitted with extensible tooling which includes jacks acting on an extensible frame within the shield and jacks which act on the tooling in the rim area. The jacks acting at the rims are incorporated on the shield. All the jacks are linked up to a common electrical control system which is responsible for straight line movement of the jack rods in response to transducers in the control circuit and individual drives for the respective jacks. One of the transducers acts as a master to adjust the remainder.</p> |
