BOORSCHILD VOOR HET BOREN VAN MIJNGANGEN OF DERGELIJKE TUNNELS.

摘要

A shield arrangement used for tunneling and mining in which a work chamber has an open front side located at the work face from which material is to be removed in tunneling and mining operations. Pressure is admitted into the work chamber for supporting the work face against crumbling and collapse. The work chamber also has supporting elements for the work face, which are selectively movable into and out of an operative position in which they support the work face. These selectively movable supports serve to replace at least partially, the support provided by the pressure medium admitted into the work chamber. The chamber has a longitudinal axis normal to the open side of the supporting elements which may be in the form of plates.