Remove the terminal wire from the negative pole of the Kobelco excavator battery. Lower the working device to the ground completely, turn off the engine, and then slowly loosen the filler cap to release the pressure in the hydraulic oil tank.
Remove the hydraulic oil tank filter and stop the oil flow with a sealing tool. When the sealing tool is not used, the oil drain plug should be removed and the remaining oil should be drained from the hydraulic oil tank and system.
Drain the oil from the shock absorber body.
The disassembly steps of the main pump assembly are as follows.
① Remove the engine cover.
② Remove the top cover of the main pump.
③ Remove the right side cover and mounting frame.
④ As shown in Figure 4.174, remove the plug from the bracket and
⑤ As shown in Figure 4-175, remove the oil supply of the front pump and the rear pump. Hard Z 7 1 plug
Hose, front and rear pump LS valve pressure hose and EPC valve bottom pressure 『十#, Figure 4-174 Disassemble the plug hose.
⑥ 
As shown in Figure 4·176, remove the oil supply hose of the main pump and the oil drain hose of the main pump, and remove the pipe clamp in the middle of the hose. Protect with turnbuckle to prevent damage to the conical sealing part of threaded joint or elbow joint
⑦ Remove the suction pipe at the bottom of the main pump. The suction pipe port is covered with a plastic cap.
⑧ Remove the partition of the engine room, as shown in Figure 4-177, remove the muffler exhaust pipe and the positioning mounting bracket.
⑨ Remove the main pump assembly.
(a) When removing, leave 2~3 mounting bolts, and remove other mounting bolts.
(b) Hang the main pump assembly, as shown in Figure 4-178, and install two guide bolts at opposite positions in the radial direction.
(c) Remove the remaining mounting bolts, and then slowly disengage them until the main pump assembly is separated from the spline shaft.
(d) Lift up the main pump assembly.
1—Engine room partition; 2—Muffler exhaust pipe; 3—Positioning mounting bracket Figure 4-177 Remove the engine room partition, muffler exhaust pipe and positioning mounting bracket
1. Installation of the main pump assembly
The installation sequence of the main pump assembly is opposite to the removal sequence. Refuel the shock absorber and fill it to the specified level through the fuel filler opening. Run the engine to circulate the oil in the system. After waiting at least 15 minutes, check the oil level again. The shock absorber refueling volume is about 0.7L.
Fill the hydraulic oil tank and fill the oil to the specified oil level through the oil filling port. Rotate the engine to circulate the oil in the system, and then check the oil level.
2. Disassembly of the main pump input shaft sealing ring
① Remove the main pump assembly.
② As shown in Figure 4-179, remove the snap ring, and then remove the spacer.
③ Pry up the seal ring with a screwdriver and remove it. When removing the oil seal, take special care to avoid damaging the shaft.
3. Installation of the main pump input shaft sealing ring
The installation sequence of the main pump input shaft sealing ring is opposite to the disassembly step. Use a press tool to press fit the sealing ring, as shown in Figure 4-180.
1—Snap ring; 2—Spacer; 3—Sealing ring Figure 4-179 Remove snap ring and spacer
1 a press-fitting tool; 2-seal ring Figure 4-180 press-fit seal ring
