| 摘要 |
PURPOSE:To inhibit the displacement of a beam produced by load fluctuations by connecting a hydraulic actuator which gives longitudinal tensile force to a PC cable and controlling a supply pressure based on a displacement quantity of the beam and changing cable tensile force accordingly. CONSTITUTION:A signal processing mechanism 20 supplies pressure oil to a plurality of hydraulic cylinders 4 from a hydraulic pump 7 and sets the whole cylinders 4 to an initial setting pressure predetermined to a setting mechanism 22 by way of a pressure detector 18. Then, a part of cables 3 connected to the cylinders 4 is locked, thereby preventing a drop in the tensile force of the cables attributable to oil leakage or the like when they are used for long time. Then, the mechanism 20 controls an unlocked cylinder 4 by way of a drive mechanism 21 based on a signal transmitted from a setting mechanism 22 which conforms to a displacement signal of the beam 1 from a displacement detector 24. Responding to an increase and decrease in a deflection quantity of a beam 1, the mechanism increases and reduces the tensile force of the cables 3. This construction makes it possible to maintain the beam in a horizontal state even when the load of the beam is fluctuated. |
