| 摘要 |
PURPOSE:To decrease a loss in pump driving power without increasing clutch capacity more than it is needed by increasing a supply pressure to a hydraulic clutch in the case of changing speed while disengaging a directly coupled clutch, and decreasing the supply pressure to the hydraulic clutch in the case of changing speed while throwing in the directly coupled clutch. CONSTITUTION:A hydraulic pressure is supplied to a directly coupled clutch 2 and respective hydraulic clutches by means of a directly coupled clutch valve 7 and a clutch control valve 8, and these directly coupled clutch valve 7 and clutch control valve 8 are controlled in operation by means of a controller 9. A variable relief valve is arranged on the discharge route of a hydraulic pump so as to adjust a supply pressure to the respective hydraulic clutches, and the directly coupled clutch valve 7 is controlled in its opening and closing operation by means of an electromagnetic switch valve, and an exciting signal is sent to that solenoid from the controller 9. The supply pressure to be supplied to the hydraulic clutch of a hydraulically actuating speed change gear is set lower in the case of throwing in the clutch 2 than that in the case of disengaging the clutch 2, so that a loss in pump driving power can be decreased without increasing a clutch capacity of the hydraulic clutch 2 more than it is needed. |
