DIRECTION CONTROL METHOD AND DIRECTION CONTROL HYDRAULIC CIRCUIT FOR TUNNEL EXCAVATOR

PURPOSE:To surely control the direction of a tunnel excavator. CONSTITUTION:A plurality of thrust jacks 5 are provided at an interval in the peripheral direction of an intermediate shield 12 between the front shield 11 and the rear shield 13 of a shield main body 1 divided into multiple parts, pressure oil is selectively fed to these thrust jacks 5 from a direction changing hydraulic pump 6 via direction selector valves 9 provided on individual thrust jacks 5 to control the direction of the shield main body 1 in a tunnel excavator. Oil pressure sources are provided for individual thrust jacks 5. Flows necessary for the direction control are fed to the thrust jacks 5 from a hydraulic source via direction control valves 10, and the direction of the shield main body 1 is controlled. The direction can be surely controlled without reducing the driving force of the shield main body 1.