| 摘要 |
PURPOSE:To eliminate the variation of operating speeds with mode switching by equalizing the discharge amounts of a pump in operations for a running power mode, a running economy mode, an excavating power mode, and an excavating economy mode. CONSTITUTION:When loads are great as in the case of climbing, a switcher 31 is turned to a power mode position P, the maximum displacement volume of an oil-pressure pump 13 is reduced, and the maximum revolving number of an engine 11 is limited to higher values. When loads are small as in the case of flat road running, etc., the switcher 31 is turned to an economy mode position E, the maximum displacement volume of the pump 13 is increased, and the maximum revolving number of the engine 11 is limited to lower values. Pump discharge amounts in the power mode and the economy mode are equalized by solenoid valves 23 and 27-30, and the variation of operation speeds with mode switching is eliminated, making the drive operations easier. |
