Shield assemblies for installation in under-ground roadways and rock excavating machines including such shield assemblies

摘要

A shield assembly for installation in an underground roadway or tunnel comprises an articulated upper shield assembly, a lower shield assembly and a plurality of hydraulic rams for urging the upper shield assembly upwards relatively to the lower shield assembly, a telescopic arrangement being provided which guides the upper shield assembly in a direction along the roadway or tunnel but which allows the end margins of the upper shield assembly to move outwardly relative to the end margins of the lower shield assembly.