Tunnel excavator with crawler drive and roof support bearing frames

Abstract

The tunnel excavator (1) includes a cutter supporting body (3) provided with cutters (2) for excavating the earth. The tunnel excavator also includes crawlers (13) for moving backwards and forwards, and upper and side bearing frames (15, 16) which move radiantly until they contact an inner surface of the excavation (12). Forwards movement is accomplished by propelling the cutter supporting body (3) with the crawlers (13) while the bearing frames (15, 16) are in contact with the inner surface of the excavation (12). Forwards movement without lateral slippage can be achieved because the cutter supporting body (3) is guided through the excavation (12) by the bearing frames (15, 16). Backwards movement is achieved by radially withdrawing the bearing frames (15, 16) from the inner surface of the excavation (12) and reversing the crawlers (13). Tunneling can therefore be accomplished regardless of the state of the floor. Internal instruments can be protected from falling earth because the earth can be supported by the bearing frames (15, 16).

Dependencies are inferred from the claim text.