| 摘要 |
PROBLEM TO BE SOLVED: To simplify a hydraulic circuit for lifting and four-wheel steering of a work machine of a tractor. SOLUTION: A spraying work machine is lifted by supplying and discharging a control flow rate to a boom lifting cylinder 27 for lifting the spraying work machine via a lifting control valve from a first hydraulic pump 28 of the tractor, and a surplus flow rate of the boom lifting cylinder 27 is supplied and discharged to front and rear steering hydraulic cylinders 31 and 32 for the four- wheel steering via a steering control valve 41 to steer front wheels and rear wheels. Lifting operation and the four-wheel steering of a pest control work machine can be performed by a single hydraulic pump so that the constitution can be simplified, and a cost can be reduced. Since spraying work is performed by fixing the pest control work machine in a rising state at pest control work, pressure oil from the first hydraulic pump 28 is smoothly supplied to the steering control valve 41 and the front and rear steering hydraulic cylinders 32 and 32 via the boom lifting cylinder 27 so that the direction of a traveling car body can be smoothly changed. |
