HYDRAULIC CLUTCH CYLINDER CONTROL DEVICE

PURPOSE:To reduce the torque for driving a pump by keeping the pump liquid pressure low except the duration of engagement of a clutch from starting of the engagement to opening of an unload valve and the duration from closing of the unload valve to opening thereof for reaccumulating pressure liquid in an accumulator. CONSTITUTION:As engagement of a clutch is started, pump liquid pressure gradually increase, and after the engagement is completed, the increase of pressure continues, and when the pressure exceeds a set pressure of an unload valve 29, the unload valve 29 is opened to drastically decrease the pressure. When the liquid pressure for engaging the clutch exceeds the set pressure of the unload valve 29, the unload valve 29 is opened and a check valve 28 is closed to drastically decrease the pump liquid pressure, and then the pump liquid pressure increases and decreases as the unload valve 29 is closed and opened. Thus, the pump liquid pressure can be kept low except the duration of engagement of the clutch from starting of the engagement to opening of the unload valve and the duration from closing of the unload valve to opening thereof for reaccumulation of the accumulator.