CPC E02F 9/2228 (2013.01) [E02F 9/123 (2013.01); E02F 9/125 (2013.01); E02F 9/128 (2013.01); E02F 9/2004 (2013.01); E02F 9/2267 (2013.01); E02F 9/2271 (2013.01); E02F 9/2285 (2013.01); E02F 9/2292 (2013.01); E02F 9/2296 (2013.01); E02F 9/24 (2013.01); F15B 13/044 (2013.01); E02F 3/32 (2013.01); E02F 3/425 (2013.01)] | 3 Claims |
1. A hydraulic system of a construction machine, comprising:
hydraulic actuators including a slewing motor;
a brake including a brake release port, the brake being switched from a brake-applied state, in which the brake prevents rotation of an output shaft of the slewing motor, to a brake-released state, in which the brake allows the rotation of the output shaft, when a hydraulic pressure led to the brake release port becomes higher than a first setting value;
control valves interposed between a main pump and the hydraulic actuators, each control valve including pilot ports;
first solenoid proportional valves connected to the pilot ports of the control valves;
operation devices to move the control valves, each operation device outputting an electrical signal corresponding to an operating amount of the operation device;
a controller that controls the first solenoid proportional valves based on the electrical signals outputted from the operation devices;
a second solenoid proportional valve connected to the brake release port by a secondary pressure line and connected to an auxiliary pump by a primary pressure line; and
a switching valve interposed between the auxiliary pump and the first solenoid proportional valves, the switching valve including a pilot port connected to the secondary pressure line by a pilot line, the switching valve switching from a closed position to an open position when a pilot pressure led to the pilot port of the switching valve becomes higher than or equal to a second setting value that is lower than the first setting value.
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