The function of the excavator control valve is shown in Figure 1-32.
The hydraulic oil of the pump P1 flows into the housing A through the oil passage inlet (P1), the central bypass oil passage 2 and the parallel oil passage 3. The hydraulic oil of the pump P2 flows into the housing B through the oil passage inlet (P2), the center bypass oil passage 2 and the parallel oil passage 3.
The hydraulic oil of the pump Pl flows directly into the oil tank through the central bypass oil passage, the negative control oil hole (NR1), the oil return passage and the oil return port (R2). The hydraulic oil of pump P2 also flows into the tank through the central bypass oil passage, negative control oil hole (NR2), oil return passage and oil return port (R2). The hydraulic oil in channels 3 and 10 is blocked and cannot return to the tank.
If the control lever is operated, the hydraulic oil of pump P2 is supplied from the channel to the right spool and from the channel to the following spools: optional, boom 1, bucket and arm 2. Moreover, when the oil of the passage is supplied to the rotary, boom 2 and arm spool, the hydraulic oil of the pump P1 is supplied from the passage to the travel left spool.
