| 摘要 |
PROBLEM TO BE SOLVED: To provide a concrete pump that is capable of reducing the reflux while arbitrarily adjusting the operation pressure of a driving cylinder.SOLUTION: A concrete pump P includes: driving cylinders 23, 24 expanding and contracting by hydraulic oil sent from a first hydraulic pump Pu1 driven by an engine En (a prime mover); pump cylinders 21, 22 connected to the driving cylinders 23, 24; a reflux oil passage 65 that is branched from an oil passage between the first hydraulic pump Pu1 and the driving cylinders 23, 24 and connected with an oil tank; and a relief valve RV provided in the reflux oil passage 65 and capable of adjusting the relief pressure. A control device C reduces the discharge flow rate of the hydraulic pump when determining that the hydraulic oil passes through the reflux oil passage. |
