| 摘要 |
PURPOSE:To maintain a uniform excavating speed by feeding hydraulic oil into a plurality of jack cylinders arranged circumferentially of a shield machine, from a pump through differential pressure setting valves so as to uniformly adjust the pressure differential between a primary pressure and a secondary pressure. CONSTITUTION:A plurality of double acting cylinders 10 are arranged in the upstream end part, in the excavating direction, of a shield machine body 7, being spaced from one another in the circumferential direction of the latter so that the shield machine body 7 is pressed against existing segments 12, and hydraulic pumps 21, 29 are adapted to thrust the shield machine body 7. Hydraulic oil is fed from the pumps 21, 29 into the cylinders 21, 29, and differential pressure valves 23 for regulating the pressure differential between primary and secondary pressures at a predetermined value, are provided for every one or every group of the cylinders 10 so that an output difference is effected in each of the cylinders 10, and accordingly, a moment for curving is given to the shield body 7. Further, hydraulic oil from the hydraulic pumps 21, 29 is fed into the cylinders 10 through the differential pressure setting values 23 so as to adjust the pressure differential so as to maintain the excavating speed at a uniform value. |
