Tunnelling shield with rotary radial cutting arms - has part of each arm attached by hinge, to swing backwards

摘要

The rotary cutting head for tunnelling operations has a cylindrical outer portion (1), with a sharp cutting edge, which is advanced by telescopic cylinders (3) mounted on a rear frame (2). Inside the outer cylinder is a central drive shaft (7) carrying radial arms (8) with rows of cutter inserts (17) projecting outwards. Each arm can be swung backwards about a hinge spindle (14) passing through the arm and through a block (12) mounted on the outer end of the drive shaft. A bolt (16) also passing through the block acts as a stop for the arm. The cylinder has a cut-out (22) in the region of the end of the arm.