Stick release condition: under stick release condition, P1 and P2 double pumps are combined to supply oil to the small chamber of stick cylinder, and the return oil from the large chamber of cylinder returns to the oil tank through stick 1 valve and stick 2 valve. Stick 1 valve and stick 2 valve are in the stick release position, the pilot valve of the locking valve is in the left position, CP2, LCA and lcat2 check valves are open, and other valve elements not involved are in the initial position.
Note: the orange line is an oil inlet; Green line - return oil circuit: purple line - pilot oil circuit; The blue line is an oil leakage road; The blank position in the valve is the working position, which is the same as later.
The hydraulic flow path of the stick release hydraulic system of Shengang excavator is shown in Figure 2.10:
When the stick release action is performed, the pressure oil from the pilot pump switches the stick 1 valve core from the stick 1 valve pilot port PBAL to the right position (release position); Switch the valve core of stick 2 to the discharge position from the pilot oil port pba2 of stick 2 valve; There is no pilot pressure oil at plc2 port, and the pilot valve is in the left position.
After the hydraulic oil from P2 pump flows into the main control valve, it is divided into middle return oil circuit P2 'and parallel oil circuit P2. However, due to the switching of stick 1 valve core, the middle return oil circuit P2 "is cut off and flows from parallel oil circuit P2. Open CP2 and LCA check valves and flow to stick 1 valve.
After the hydraulic oil from P1 pump flows into the main control valve, it is divided into middle return oil circuit P1 'and parallel oil circuit P1. Due to the switching of stick 2 valve core, the middle return oil circuit P1' is closed, and the parallel oil circuit P1 has throttle valve lcap2. The hydraulic oil opens check valve lcat2 and flows to stick 2 valve. The discharge oil of P1 pump and P2 pump merge inside the valve, push open the cone valve CRAR of the stick locking valve, pass through CRAR, and flow from the Ba port of the main control valve to the small cavity side of the stick cylinder to push the stick to discharge.
The return oil from the large chamber of stick cylinder enters the AA port of the main control valve, flows through stick 1 valve and stick 2 valve, and returns to the oil tank from the return oil circuit.
