Tunnel boring machine whose driving shaft (4) adjacent to the boring head (6) is journalled in a bearing (12) which is intended to take up only radial forces. Shaft (4) is at its other end journalled in bearings (13,14) which take up both radial and axial forces.

A tunneling machine adapted to cut tunnels on a continuous basis and to apply continuous pressure on the tunnel face even during repositioning of the gripping legs is disclosed. The machine includes at least two supporting frames having a plurality of extendible feet which are adapted to grip the tunnel wall. The support frames are provided with axial bores therethrough, and a hollow piston extends through all of the bores for longitudinal movement along the axis of the tunnel. In accordance with the method, a tunneling operation is carried out by extending at least one pair of extendible feet against the walls of the tunnel to securely hold at least one of the support frames relative to the tunnel wall. The piston chamber of each support frame which is clamped to the wall is pressurized to drive the cutter head against the face of the tunnel. While the cutter head is being advanced in this manner, unclamped support feet are moved forward to a clamping position to take over when the first-mentioned support feet reach the end of their effective stroke. This operation is repeated to apply continuous thrust pressure to the cutting head.

A tunnel boring machine having increased thrust capability is disclosed. The machine includes a rotatable cutter head for cutting material away from the face of the tunnel and a drive shaft and motor for rotating the cutter head in a cutting state of operation. A bearing assembly is also provided for facilitating rotation of the cutter head during the cutting state of operation. Thrust cylinders are also provided for generating forward thrust. The machine also includes first and second structures for defining a fluid pressurizable cavity between the cutter head and the thrust cylinders which transmit forward thrust to the cutter head when the cavity is sufficiently pressurized. In addition, the machine includes a pressurizing system for pressurizing the cavity.

There is disclosed a hard rock trench cutting machine comprising a main body assembly and a cutting wheel assembly. A cylinder is transversely mounted on the main body assembly and carries a pair of pistons which extend axially from each end of the cylinder. Pads are provided on each piston to bear against the sidewalls of a trench. Each piston has an end face within the cylinder which, together with an inner sidewall of the cylinder, comprises a pressure chamber adapted to force the pads against the trench. The main body and its cylinder are free to move laterally relative to the pistons when the cylinder is pressurized. Extensible arms are provided between the pistons and the main body assembly for forcing the main body assembly and its cutting wheel forwardly to progressively cut a trench. A steering assembly is provided to shift the main body assembly laterally relative to the pistons and about the central axis of the cutting wheel.

The invention relates to a trench wall cutter with a cutting frame and a gear shield attached thereto. There is at least one cutting wheel positioned to turn on the opposite shield sides, and on it roller-shaped excavation tools distributed over the periphery are pivotally mounted. When the cutting wheel is rotating the tools form a cutting wheel cutting surface which runs essentially axially parallel to the axis of rotation of the cutting wheel. To accommodate horizontal forces, at least one additional roller is pivotally mounted on each cutting wheel, the axis of the additional roller being directed substantially radially with respect to the axis of rotation of the cutting wheel. One jacket surface of the roller on the radial face side of the cutting wheel away from the gear shield projects in the direction of the axis of rotation of the-cutting wheel.