| 摘要 |
PURPOSE:To prevent abnormal increase of clamping force of a hydraulic cylinder and prevent thrusting of a wedge-shaped fastening device by supplying pressure oil at all times to the unclamping oil chamber of each hydraulic cylinder in an oil pressure wedge double force type clamping device, and switching the oil to the clamping oil chamber from supply to discharge. CONSTITUTION:In an oil pressure wedge double force type clamping device of a working machine, an unclamping oil chamber 19 and a clamping oil chamber 18 of each hydraulic cylinder 15 are connected to a discharge port 21a of common hydraulic pump 21, and a direction changing valve 22 is provided in the oil passage to each clamping oil chamber 18 to enable supply of pressure oil. At the same time, a check valve 23 that checks counter flow from the clamping oil chamber 18 is provided, and the clamping oil chamber 18 and unclamping oil chamber 19 are connected by a connecting passage through a clamping pressure oil liberating device. When oil pressure of each unclamping oil chamber 19 is lowered abnormally, pressure oil is liberated from each clamping oil chamber 18 to the unclamping oil chamber 19 and abnormal increase of clamping force of the pressure oil cylinder 15 is prevented. |
