Open trench operated driving shield - has variable length hydraulic cylinders linking rear wall sections to shield

摘要

The shield is for driving forward in an open trench, with a clear interior space sealed at the rear end by a support wall connected to the shield. This wall is made up from wall sections set on top of each other, led along the axis of the drive. The wall sections above the bottom one, at least, are connected to the shield or attached components by tension, or tension-and-pressure members (hydraulic cylinders) which are of variable length. In their advanced thrust position, wall sections may terminate with the rear end of the sidewalls. This permits provision of increased and more even density in the filled earth.