| 摘要 |
<p>This invention relates to a hydraulic circuit apparatus for a hydraulic excavator which can change the supply oil quantity from two hydraulic pumps to a boom and to an arm cylinder by merely operating a boom operation lever and arm operation lever for operating a boom operation valve and arm operation valve, respectively, in order to control the operation power and operation speed of the boom and arm cylinder. This hydraulic circuit apparatus includes an arm deceleration change-over valve (29), a boom deceleration change-over valve (37), a boom acceleration change-over valve (25), an arm acceleration change-over valve (42), a boom operation valve (54) operated by a boom operation lever (65) so as to switch between the boom deceleration and acceleration valves, an arm operation valve (52) operated by an arm operation lever (66) so as to switch between the arm deceleration and acceleration valves, and an arm operation mode change-over valve (60).</p> |
