| 摘要 |
PURPOSE:To attain the saving of energy, permit every type of composite operations, and raise the rapidity of boom operation by using a system in which the pressure oil of the third pump is jointed with a boom switching valve through the switching valve of a soil-moving plate in a three-pump system with the soil- moving plate. CONSTITUTION:A turning switch valve 23 and a left-handed running switch valve 24 are connected in parallel to the first pump 16, and a bucket switching valve 19 is connected in series to a turning motor 14. On the other hand, an arm switching valve 20, a boom switching valve 21 and a right-handed running switch valve 25 are connected in parallel to the second pump 17. The switching valve 22 of the soil-moving plate is connected to the third pump 18. When operations other than those by the soil-moving plate 9 are made, the pressure oil of the third pump 18 is jointed into the boom switching valve 21 through the valve 22. All amounts of pressure oil to the turning motor 14 are thus supplied to a bucket cylinder 10 and thereby the composite operations in the same pump system are made possible. When the arm 6 and the boom 7 are in concurrent operation, the pressure oil of the third pump can be sent to the boom. |
