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AssigneeHitachi Construction Machinery Co., Ltd.
InventorsKazuhiro Sunamura, Osamu Tomikawa, Shigehiro Yoshinaga, Toichi Hirata
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To provide a burglarproof device for a hydraulic machine which has a high degree of security against burglary, ensures high safety, and can be simply installed in a location where the device is hard to find for burglars, a solenoid valve 23 of a burglarproof device 20 is installed in a pilot primary pressure line 3 between a pilot hydraulic pump 1 and a pilot valve device 4. Unless ten numeral keys 21a of a key input device 21 are depressed in the order of the password, an unlocking electronic circuit 22K does not generate an unlock signal and the solenoid valve 23 keeps the pilot primary pressure line 3 cut off. Therefore, a pilot primary pressure from the pilot hydraulic pump 1 is shut off and, even with a manual lever 4c of the pilot valve device 4 operated, no pilot secondary pressure is produced and a main control valve 6 is kept standstill. As a result, a hydraulic cylinder 8 is not operated and the hydraulic machine is unable to move.
A burglarproof device for a hydraulic machine provided with a hydraulic system comprising a main hydraulic system including a main hydraulic pump driven by a prime mover, a plurality of actuators driven by a hydraulic fluid delivered from said main hydraulic pump, and a plurality of main control valves for controlling respective flow rates of the hydraulic fluid supplied from said main hydraulic pump to said plurality of actuators;
Dependencies are inferred from the claim text.