Direction correcting device for shield tunnelling machine

A direction correcting device for a shield tunnelling machine having a shield body provided with a head portion and a tail portion following the head portion, comprising:

• four connecting means disposed around an axis of said tail portion at angular intervals, where
• three of the four connecting means are provided with a jack having two connecting portions relatively displaceable in the axial direction of said tail portion, each jack being connected at one of said connecting portions to said head portion and at the other of said connection portions to said tail portion;
• and
• the fourth connecting means is provided with a connecting body having two connecting portions incapable of relative displacement in the axial direction, the connecting body being interconnected at one of said connecting portions to said head portion and at the other of said connecting portions to said tail portion to permit said head and tail portions to relatively swing and to prevent said head and tail portions from relatively displacing in the axial direction.