Main-ancillary tunnel excavator

A main-ancillary tunnel excavator comprising a main machine including a main front cylinder, a main rear cylinder, a main propulsion jack connecting said main front cylinder and said main rear cylinder, and main grippers mounted on said main front cylinder and said main rear cylinder which take the reaction forces at walls excavated by said main machine;

• an inner cutting disc and outer cutting ring surrounding said disk positioned on a front face of said excavator;
• a pivotable housing which turns inside said main machine;
• and an ancillary machine housed inside said pivotable housing and including an ancillary front cylinder, an ancillary rear cylinder, an ancillary propulsion jack connecting said ancillary front cylinder and said ancillary rear cylinder, and ancillary grippers mounted on said ancillary front cylinder and said ancillary rear cylinder which take the reaction forces at the walls excavated by said ancillary machine;
• wherein the inner cutting disc of the main machine serves a dual purpose as a cutting disc of the ancillary machine.

A method of tunneling comprising the steps of:

• excavating a main tunnel with a main tunnel excavator including a front cylinder, a rear cylinder, a propulsion jack connecting said front and rear cylinders, and grippers which take the reaction force at the excavated walls while said tunnel excavator is excavating,
• providing a pivotable housing turnably mounted in said main tunnel excavator,
• removably housing an ancillary tunnel excavator inside said pivotable housing, said ancillary tunnel excavator including an ancillary front cylinder, an ancillary rear cylinder, an ancillary propulsion jack connecting said ancillary front cylinder and said ancillary rear cylinder, and ancillary grippers mounted on said ancillary front cylinder and said ancillary rear cylinder which take the reaction forces at the walls excavated by said ancillary tunnel excavator while said ancillary tunnel excavator is excavating,
• at a position along said main tunnel where a crosscut is desired, turning said pivotable housing to face the position and excavating the crosscut with said ancillary tunnel excavator.

A method of tunneling comprising the steps of:

• providing a main tunnel excavator including a front cylinder, a rear cylinder, a propulsion jack connecting said front and rear cylinders, an inner cutting disc and outer cutting ring surrounding said disk positioned on a front face of said excavator, a pivotable housing which turns inside said main excavator, and grippers which take the reaction force at the excavated walls while said tunnel excavator is excavating,
• excavating a main tunnel with said outer cutting ring and said inner cutting disc,
• removably housing an ancillary tunnel excavator inside said pivotable housing, said ancillary tunnel excavator including an ancillary front cylinder, an ancillary rear cylinder, an ancillary propulsion jack connecting said ancillary front cylinder and said ancillary rear cylinder, and ancillary grippers mounted on said ancillary front cylinder and said ancillary rear cylinder which take the reaction forces at the walls excavated by said ancillary tunnel excavator while said ancillary tunnel excavator is excavating, said inner cutting disc of said main tunnel excavator serving as the cutting disc of said ancillary tunnel excavator,
• at a position along said main tunnel where a crosscut is desired, turning said pivotable housing to face the position and excavating the crosscut with said inner cutting disc serving as the cutting disc of said ancillary tunnel excavator.