| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems of a tractor performing the rolling control by a right or a left hydraulic cylinder causing the increase of the stroke of an active cylinder to necessitate a hydraulic pump having high capacity because of the constant height of the supporting point of the lift rod side the delay of the action keeping the height or the laterally inclined posture and the inconvenient handling in attaching and detaching of a heavy linking matter. SOLUTION: In the case of driving a lift arm of a tractor with individual hydraulic cylinders 2, 2, the hydraulic oil from a pump P is branched by the switching operation of the 1st control valve 1 to supply the equal quantity of hydraulic oils to both cylinders 2, 2 by a lift-controlling circuit 3 connected to the cylinder. A rolling control circuit 5A to add the hydraulic oil sent from the pump P through a separate path to the lift control circuit 3 by the switching operation of the 2nd control valve 4 is connected to either one of the above control valve 1 and the lift control circuit 3 between the cylinders 2, 2.
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