| 摘要 |
PURPOSE:To easily switch horizontal excavation to circular excavation or vice versa by connecting the extending and shrinking chambers of cylinder for correction provided between a link and an arm through a switch valve to the extending and shrinking chambers of cylinder for boom and a drain. CONSTITUTION:When an arm cylinder 19 is extended and an arm 4 is moved upwards in a rocking manner around a pin 3 as a center by using the first and second switch valves 301 and 302 as I, the pin 15 in a circle (a) where the pin 3 is centered, and the pin 16 of the first link 12 moves in a circle (b) where the pin 14 is centered. For this reason, the second link 13 moves in a rocking manner where the pin 15 is centered in relation to the arm 4, and a cylinder 22 extends. Pressure oil in the chamber 22b of the cylinder 22 is supplied to the chamber 9b of the cylinder 9, the cylinder 9 contracts, and the boom 2 moves downwards in a rocking manner around the pin 1 as a center. A bucket 6 thus moves horizontally forwards for horizontal excavation work. Also, when using a switch valve 35 as III, usual circular excavation can be attained. |
