FRONT ATTACHMENT HYDRAULIC CIRCUIT DEVICE FOR CIVIL ENGINEERING AND CONSTRUCTION MACHINE

PURPOSE:To enlarge the driving force of a mother machine and make a device compact by providing a hydraulic circuit, formed of a hydraulic pump, a hydraulic cylinder and a direction switching valve, with a booster means for boosting pressure oil through the direction switching valve to perform supply to the hydraulic cylinder. CONSTITUTION:A hydraulic circuit device is formed by disposing a direction switching valve between a hydraulic pump 1 and a hydraulic cylinder 2. A booster 10 formed of a hydraulic drive part 10a and a high pressure generating part 10b is disposed between the direction switching valve 3 and the hydraulic cylinder 2 to form a booster means. A circuit between the pump 1 and the hydraulic cylinder 2 is connected to a port 2a by main circuits 7, 8, a high pressure circuit 18 from the high pressure part 10b, and the like through the direction switching valve 3, and the circuit from the high pressure part 10b is connected to a port 2b by a suction circuit 15, a discharge circuit 16, a main circuit 9, and the like. The driving force of a mother machine can be thereby enlarged, and the device is made compact.