Driving shield for tunnel or mine gallery - uses pressurised cylinders with releasable stops blocking outward thrust of blades

摘要

Driving blades are pressed forward by hydraulic cylinders sited between individual blades and the progressing support frame, on the machine for driving tunnels or mine galleries below ground. Use is made of stop devices blocking the outward thrust of the blade cylinders. The blocking action is automatically removable when the piston chambers are subjected to pressure. The stop devices can be releasable return valves, blocking the cylinders' annular spaces against return. Operational reliability and controlability are enhanced.