| 摘要 |
PURPOSE:To make it possible to perform ascent-descent control through an ascent-descent control valve while performing clutch control by forming an ascent-descent control circuit by connecting a hydraulic pump through a throttle valve to the ascent-descent control valve in a clutch control circuit. CONSTITUTION:The ascent-descent control valve 20 of an ascent-descent control circuit 21 is operated to raise or lower a working device, such as a reaping device, mounted on a machine body. The ascent-descent control circuit 21 can receive hydraulic pressure from a hydraulic pump 22 through both a clutch control circuit 17 branched off via a clutch control valve 18 and a bypass circuit having a throttle valve 23 and not going via the clutch control valve 18. Consequently, the ascent-descent control circuit 21 can always receive the hydraulic pressure through the bypass circuit having the throttle valve 23 regardless of whether a main clutch has been engaged by the clutch control valve 18 or not to cause the ascent-descent control valve 20 to perform ascent-descent control.
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