| 摘要 |
PROBLEM TO BE SOLVED: To conduct leveling control free from any disturbance even in a large load from a working table, without enlarging a size of a leveling cylinder. SOLUTION: This leveling device is provided with a leveling control valve 35 for controlling oil pressure supply to the leveling cylinder 23 in response to turn-up and -down of a boom to hold the working table in a horizontal condition, a continuous delivery type hydraulic booster unit 60 for amplifying the oil pressure supplied to the leveling cylinder, and a working table load detector 45 for detecting the load acting on the cylinder from the working table. When the load detected by the detector 45 is a prescribed value or less, direct oil pressure supply from a hydraulic pump P to the leveling cylinder is carried out without using the booster unit 60. When the load detected by the detector exceeds the prescribed value, the oil pressure from the pump P is amplified by the booster unit 60 to supply it to the cylinder 23.
|
