Tunnelling machine shield having fluid circulating bulkhead and rotary cuting head

Claim 1

TUNNELLING EQUIPMENT COMPRISING A TUNNELLING SHILED INCLUDING A TRANSVERSE PRESSURE BULKHEAD, A ROTARY DIGGING HEAD MOUNTED WHOLLY IN FRONT OF SAID BULKHEAD, THE ROTARY DIGGING HEAD CARRYING MULTIPLE DIGGING MEMBERS, THE MAXIMUM EFFECTIVE DIAMETER OF THE DIGGING MEMBERS BEING APPROXIMATELY EQUAL TO THE DIAMETER OF THE SHIELD, AND SAID DIGGING HEAD ALSO CARRYING MULTIPLE DEFLECTOR SURFACES FOR LIFTING AND DISCHARGING SPOIL REARWARDLY, ROLLER THRUST BEARINGS LOCATED INSIDE THE WORKING CHAMBER DISTRIBUTED AROUND THE PERIPHERY OF THE DIGGING HEAD AND ACTING BETWEEN THE TUNNELLING SHIELD AND THE DIGGING HEAD TO LOCATE THE DIGGING HEAD IN RADIAL AND AXIAL DIRECTIONS, MULTIPLE DRIVING MOTORS LOCATED AT THE REAR OF THE BULKHEAD AND EACH CONNECTED VIA A DRIVE SHAFT PASSING THROUGH THE BULKHEAD TO A DRIVING PINION AT THE FRONT OF THE BULKHEAD WITHIN THE WORKING CHAMBER, AN ANNULAR PIN WHEEL OR GEAR RING SECURED TO THE DIGGING HEAD, TO BE ENGAGED BY SAID DRIVING PINION, PACKING MEANS ADAPTED TO BE ENGAGED BETWEEN THE SHIELD AND A STATIONARY ANCHORAGE, FOR FORCING THE SHIELD FORWARDLY IN THE TUNNEL, SUPPLY DUCT MEANS THROUGH THE BULKHEAD FOR DELIVERING A LIQUID THIXOTROPIC SUSPENSION UNDER PRESSURE TO THE WORKING CHAMBER, AND DISCHARGE DUCT MEANS THROUGH SAID BULKHEAD, AT A POINT SPACED FROM THE ROTARY AXIS AND ABOVE THE BOTTOM THEREOF FOR DISCHARGING SPOIL MIXED WITH SAID SUSPENSION REARWARDLY FROM SAID WORKING CHAMBER.