| 摘要 |
PROBLEM TO BE SOLVED: To efficiently merge and supply the pressure oil, in construction machinery having a first to a third line connected with a first to a third pump respectively, from the third pump with the first line to which the pressure oil from the first pump is supplied, as well as the second line to which the pressure oil from the second pump is supplied. SOLUTION: The hydraulic circuit includes the followings: a first confluent passage capable of supplying the pressure oil from the third pump to a first unloaded passage of the first line, a second confluent passage capable of supplying the pressure oil from the third pump to the second supply passage of the second line, a discharging passage connecting the first confluent passage/the second confluent passage with a tank and also having a throttle, and finally a confluent switching valve having a communication position for discharging the pressure oil from the third pump to the tank via the discharging passage and a restricting position for shutting off the discharging passage or restricting the discharging amount from the communication position. When a second direction switching valve specified of the second line is operated, the switching valve is switched from the communication position to the restricting position. COPYRIGHT: (C)2009,JPO&INPIT
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