| 摘要 |
PURPOSE: A boom and arm composite control circuit of an excavator is provided to simplify high load precision-composite works by solving the imbalance of motion according to the imbalance of the pressure of each cylinder on the composite motion of an arm cylinder and a boom cylinder. CONSTITUTION: A boom and arm composite control circuit of an excavator comprises the steps of: including a primary main pump(11) and a secondary main pump(21); connecting a primary boom control spool(13) and a primary arm control spool(14) in order from the upper reaches along a primary bypass line(12) to the primary main pump; connecting a secondary boom control spool(23) and a secondary arm control spool(24) in order from the upper reaches along a secondary bypass line(22) to the secondary main pump; connecting additional parallel lines(15a,15b) linked with the primary bypass line to the primary boom control spool and the primary arm control spool; connecting additional parallel lines(25a,25b) connected with the secondary bypass line to the secondary boom control spool and the secondary arm control spool, wherein the parallel line(25b) is connected to the secondary arm control spool through the primary bypass line of the primary arm control spool and an arm joint circuit(17); connecting the primary boom control spool and the secondary boom control spool through a boom joint circuit(16); and connecting the secondary control spool with an arm cylinder(2).
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