| 摘要 |
PURPOSE:To reduce the weight of an excavator by making the diameter of the tube of the first boom cylinder smaller by a method in which a quadrilateral form is formed by the pivotal joint portion between both ends of the first boom and the pivotal joint portion between both ends of the second boom cylinder, and the first boom cylinder is provided on the diagonal line of the quadrilateral form. CONSTITUTION:An excavator consists of a slewing frame 3, the first boom 15, the second boom 16, an arm 7, and a bucket 8. A quadrilateral form is formed by the first pivotal joint portion 21 and second pivotal joint portion 22 between both ends of the first boom 15 and the third pivotal joint portion 23 and the fourth pivotal joint portion 24 between both ends of the second boom cylinder 20. The first boom cylinder 19 is provided on the diagonal line connecting the joint portion 22 with the joint portion 23. Since it follows that the second boom cylinder 20 is positioned below the first boom cylinder 19, even when load P applies to the bucket 8, the cylinder 19 receives only compressive forces usually. The diameter of the tube of the first boom cylinder can thus be made smaller. |
