| 摘要 |
PURPOSE:To reduce the equipment cost by setting an oil pressure in the cylinder on the tilting direction side lower than that in the cylinder on the opposite side between the front and rear balance cylinders tilting a supporting member. CONSTITUTION:Balance cylinders 8f and 8r are provided with independent pressure oil supply sources, respectively; a selector valve selecting 3 positions of high, intermediate, and low pressures is set in an oil hydraulic circuit of a pressure oil supply system. In the case that a top carriage 3u and top frame 4 are tilted from a horizontal state to the left side, an oil pressure in the balance cylinder 8r near a screwdown point Ar of the rear screwdown screw 7r being the tilt supporting point is set lower than that in the opposite side cylinder 8f so that a working force FA is lowered than a working force FB. In this method, a small-sized device is available because both a reaction force at screwdown points Af and Ar and a difference between both reaction forces are reduced, so that the equipment cost is reduced.
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