Stick empty bucket retraction - normal regeneration: when the stick empty bucket retracts, the combined flow of P1 and P2 pumps supplies oil to the large cavity of the stick cylinder, and the return oil from the small cavity of the cylinder is regenerated or returned to the oil tank through the stick 2 valve. The stick 1 valve is in the retracted position, the stick 2 valve is in the normal regeneration position, the pilot valve of the locking valve is in the right position, the CP2, LCA and lcat2 check valves are open, and the other valve elements not involved are in the initial position.
The liquid flow path of the hydraulic system for empty bucket retraction of the stick is shown in Figure 2.11:
When the stick is in the empty bucket retraction operation, the pressure oil from the pilot pump switches the stick 1 valve core from the stick 1 valve pilot oil port Paal to the left position (retraction position); Switch the valve core of stick 2 to the normal regeneration position from the pilot oil port paa2 of stick 2 valve; Switch the pilot valve core from the pilot oil port plc2 of the pilot valve of the locking valve to the right position. The spring cavity of the cartridge cone valve CRAR is connected with the leakage oil circuit, causing it to open.
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 the hydraulic oil flows to parallel oil circuit P2. Open CP2 and LCA check valves and enter stick 1 valve.
After the hydraulic oil from the PL pump flows into the main control valve, it is divided into the middle return oil circuit P1 'and the parallel oil circuit pl. due to the switching of the valve core of stick 2, the middle return oil circuit P1' is closed, and the parallel oil circuit P1 has a throttle valve lcap2. The hydraulic oil opens the check valve lcat2 and flows to the stick 2 valve. The discharge oil of P1 pump and P2 pump merge internally and flow from AA port of the main control valve to the large chamber side of the stick cylinder to push the stick to retract.
The return oil from the small chamber of the stick cylinder enters the Ba port of the main control valve, passes through the open cone valve CRAR of the stick locking valve, and enters the stick 2 valve through the stick 1 valve.
As the valve core of stick 2 is switched to the normal regeneration position, the channel to the oil tank will be throttled, the return oil pressure will increase, the check valve inside the valve core of stick 2 will open, and the return oil will flow to the large cavity of stick cylinder to realize the regeneration function.
When the stick is empty, there is throttling on the oil return passage to the oil tank, the pressure in the small chamber of the oil cylinder is greater than the pressure in the large chamber of the oil cylinder, the one-way valve in the valve core of stick 2 will be opened, and the return oil will be regenerated to the large chamber of the oil cylinder to realize the energy recovery of stick empty recovery. Due to its own weight, the bucket rod retracts very fast, and the oil supply in the large chamber is insufficient, which is easy to produce vacuum. Therefore, the return oil is regenerated to the large chamber to prevent empty suction and provide work efficiency.
