1. Disassembly of the control valve assembly
Run the engine at a low idle speed, operate the cylinder to the end of its stroke without overflowing the oil circuit, lower the working device to the ground, and then extinguish the engine to release the pressure in the hydraulic circuit. After turning off the engine, complete the following tasks.
① Slowly loosen the filler cap to release the pressure in the fuel tank.
② Operate the control lever several times to release the pressure in the accumulator.
③ Start the engine and run it at idle speed for about 5 seconds, then stop the operation and operate the control lever. Repeat the above operation several times to completely release the remaining pressure.
2. The disassembly steps of the control valve assembly are as follows:
① Open the engine cover, as shown in Figure 4-181, and remove the valve top cover and the air filter top cover.
② Remove the cover of the partition plate between the engine and the control valve and the top cover of the bulkhead under the oil suction pipe close to the engine.
③ As shown in Figure 4-182, remove the drain pipe and hose clamp of the pump.
Remove the self-reducing valve. Pay attention to the different lengths of the mounting bolts when removing. The length of the left mounting bolts (2 pcs) is 120 m, and the length of the right mounting bolts (2 pcs) is 125 mm.
⑤ Remove the hose between the control valve and the interruption block, the hose between the control valve and the adjusting valve, the travel valve pilot tube, the 2 boom valve pilot tubes and the 2 overflow pilot tubes as shown in Figure 4-183. catheter. Before removing the hoses, attach a label to distinguish them. Use casing nuts to protect the threaded joint and the conical sealing part of the elbow joint to avoid damage.
⑥ Disconnect the connecting hoses of the two travel valves.
⑦ As shown in Figure 4-184, remove the two LS valve pilot tubes. After disassembling the hose, attach a label to distinguish it.
⑧ Disassemble the adjusting valve and drain pipe.
⑨ Disassemble 10 hoses connecting each valve, as shown in Figure 4-185. After removing these hoses, label them
① As shown in Figure 4-186, disassemble each bucket valve tube, boom valve tube and stick valve tube.
? Disassemble each right travel valve tube, rotary valve tube and left travel valve tube.
? Disassemble the 2 LS valve pilot tubes.
?As shown in Figure 4-187, hang the control valve assembly, then remove the mounting bolts and hang down the control valve assembly.
3. Control the installation of the pump assembly
The installation sequence of the control pump assembly is opposite to the removal sequence.
Fill the hydraulic oil tank and fill the oil to the specified oil level through the oil filler. Run the engine to circulate the oil in the system, and then check the oil level again.
Drain air from the oil path between the control valve and the hydraulic cylinder.
4. Decomposition of control valve assembly
The exploded view of the control valve is shown in Figure 4-188.
When the safety valve is installed on the machine, the limit pressure of the safety valve cannot be adjusted, so it cannot be disassembled.
