Case CX50B Tier 4 Compact Crawler Excavator Service Manual 87481010 - PDF DOWNLOAD

SERVICE MANUAL

COMPACT CRAWLER EXCAVATOR CX50B TIER 4

87481010 EN-US

Issued 01Jan 08

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

CHAPTER 1 - HYDRAULIC SYSTEM

Hydraulic Circuit Diagram

401

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

202 MAIN RELIEF VALVE P3

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

203 OVER LOAD RELIEF VALVE

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

Figure 1

GRAPHIC_1D

5-16090 EN-US

No.

Issued 01-2008

Bur

1-5

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

CHAPTER 1 - HYDRAULIC SYSTEM

HYDRAULIC CIRCUIT OPERATION

Neutral Circuit

Color Coding Standard For Hydraulic

(1)Pilot Circuit

Blue : Feed, drain circuit, less than 0.34 MPa (50 psi) Green : Return, make-up circuit, 0.34~ 0.59 MPa (50~86 psi) Purple : Secondary pilot pressure, 0.59~3.5 MPa(85~508 psi) Red : Primary pilot pressure, 3.5~3.9 MPa (508~ 566 psi) Orange : Main pump drive pressure, 4.9~23 MPa (711~3340 psi) Blue tone : At valve selection Red valve : When proportional valve (reducing) is operating Red solenoid : In active and exciting Displaying the flow circuit and standby circuit when operating.

Regarding the electrical symbols in this manual, refer to the electric circuit diagram.

1. Pilot Primary Pressure Circuit The oil delivered from the A4 port on pump assy (1) enters into the solenoid valve (13) through the line filter (19).

The pressurized oil from the por t A2 of the solenoid valve (13) with the safety lock lever released (in the operating condition) is supplied to the P ports of the pilot valves for attachment (11), travel (12) and dozer (14).

Since the operating circuit is fully closed in the neutral position, the oil delivered by the pump other than the oil supplied to the Pi3 port of the control valve loses its flowing passage, and returns to the hydraulic tank (26) through the relief valve (set pressure : 3.5MPa [508 psi]) built in the solenoid valve (13).

The oil supplied to the Pi3 port is led to the tank passage through the pilot passages provided to the service spool and through the pilot passages provided to the right and left travel spools.

2. Pilot Secondary Pressure Circuit While the pilot valves (11),(12) and (14) are being in neutral, the pilot secondary pressure is not generated.

By means of operating the operating lever, the secondary pressure is generated in accordance with its motion and led to the control valve (2) from the pilot valve to shift each spool of shifting valve.

(2)Main Circuit 1. Variable Pump Circuit The delivered oil from A1 and A2 por ts on variable pump enters into P1 and P2 ports on control valve (2) respectively.

All the discharged oil from these two ports finally returns to the hydraulic oil tank (26), through each valve of travel left, boom and bucket for the P1 oil, and through each valve of travel right, swing, service and arm for the P2 oil.

2. Third Pump Circuit The oil delivered from A3 por t on 3rd pump enters into P3 port on control valve (2).

The whole amount of oil discharged through the port P3 returns to the hydraulic oil tank (26) through the selector valves for the dozer and slewing and the independent travel and flow conflux valves.

1-6

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 2

GRAPHIC_1D

NERTRAL CIRCUIT 5-16090 EN-US

Issued 01-2008

Bur

1-7

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Travel Operating Circuit Pilot oil hydraulic system with operating lever 2nd Speed Operating Circuit (Independentforward travel) (1)Pilot Circuit 1. Shifting signal for 2nd speed travel When the "Rabbit and Turtle" mark (at the power cut-off, it automatically takes back for 1st speed) on the nob of travel right lever is pushed down, it actuates the 1st and 2nd speed travel shifting valve of solenoid valve (13).

The pressurized oil signal for 2nd speed is generated from the A1 port of solenoid valve(13), and led to the P port on travel motor (4) through swivel joint (10), and shifts the 2-speed shifting valve (404).

2. Changing travel valve spool The pilot secondary pressure is generated from pilot valve (12) by the operation for travel forward.

The pressurized oil is led to the Pb3 and Pb4 ports on control valve (2) to shift the travel valve spool.

B. When the motor reaches near to a selfrunning condition (over-running) at going down a slope and so on, the oil pressure of supply side gets down to lower pressure, and the counter balance valve [brake valve] (408) spool moves to the neutral position with the spring force.

As the results, the passage in return oil side is throttled, and the motor speed is suppressed by a back-pressure, then the motor is controlled to the speed corresponding to the supplied oil volume of the pump.

C. The counterbalance valve spool is so designed that it is gradually shifted by a throttle effect to stop or star t the motor absorbing shock at the start and stop of the machine.

D. When load increases during high speed travel, the speed automatically shifts to the 1st speed, resulting in low speed and high torque.

(2)Main Circuit 1. Circuit up to Travel Motor (4) The delivered oil from A1 and A2 por ts on variable pump enters into the P1 and P2 ports of control valve (2), and led to the B3 and B4 ports through the travel valve.

Then it is led to the A and B ports on left and right travel motors respectively through the swivel joint (10).

2. Travel Motor A. The pressurized oil supplied to the travel motor shifts the spool of the counterbalance valve (brake valve) (408), releases the parking brake (403), opens the hydraulic circuit having closed by the check valve (407) and rotates the travel motor.

It actuates the speed shifting valve (404) when the 2nd speed signal is sent. The high pressure oil pumped through the shuttle valve (406) passes the speed change valve (404), actuates the 2-speed shifting piston (401) and provides the motor with high speed and low torque.

1-8

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 3

GRAPHIC_1D

TRAVEL CIRCUIT: TRAVEL FORWARD OPERATION AT TRAVEL 2ND SPEED 5-16090 EN-US

Issued 01-2008

Bur

1-9

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Slew Operating Circuit Pilot oil hydraulic system with operating lever Slew (left) Operating Circuit (1)Pilot Circuit 1. Slew Valve Spool Shifting With operation for slew (left), the pilot secondary pressure oil is generated from the pilot valve (11), and led to the Pb8 port of control valve (2) to shift the slew valve spool.

2. Releasing Parking Brake The pilot primary pressure is always led to PB port on the timer valve (303).

With the slew operation, the operating pilot secondary pressure is led to PP port on the timer valve (303) through the shuttle valve (15) to shift the spool.

It leads the pilot primary pressure 3.5 MPa (508 psi) to the parking brake to release it. (Similarly, the arm in operation releases the slew brake.)

3. Activating Parking Brake When the slew operating lever is returned to neutral position to stop slewing, the pilot secondary pressure disappears causing to shift the timer valve (303), then the pressurized oil is shut down.

The oil in the brake cylinder is discharged due to spring force, and drained through the throttle in the timer valve (303).

Thus the braking is activated with some time lag for 2.5 to 5.0 seconds to smoothly absorb the slewing inertia at its stop of motion.

(2)Main Circuit 1. Supply Circuit for Slewing Motor (3) The oil delivered from the A3 port on hydraulic oil pump (1) is supplied to the B port on slewing motor (3) through the P3 port on control valve (2) and slew valve to drive the slewing motor.

2. Slewing Motor (3) A. The relief valve (304) relieves rapidly increased pressure at start and stop of the machine to ease shock.

B. The make-up valve (check valve) (305) has a function to replenish oil from the return oil circuit that is led to the tank [T2 por t on control valve (2)] to the slewing motor, to prevent the slewing motor from the cavitation due to negative pressure generated in it because of inertia on the slewing mass.

1-10

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 4

GRAPHIC_1D

SLEWING CIRCUIT: SLEWING LEFT OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-11

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Bucket Operating Circuit Pilot oil hydraulic system with operating lever Bucket Digging Operation Circuit (1)Pilot Circuit 1. Bucket Spool Shifting When the operating lever is put at bucket digging position, the pilot secondary pressure oil is g e n e ra t e d f r o m t h e p i l o t va l ve ( 1 1 ) . T h e pressurized oil entered into the Pb1 port on control valve (2) shifts the bucket valve spool.

(2)Main Circuit 1. Supply Circuit for Cylinder (7) The oil delivered from A1 port on variable pump of pump assembly (1) enters into P1 port on control valve (2). The pressurized oil from B1 port through bucket valve is supplied to the head side of bucket cylinder (7) to activate the digging work.

The return oil from the rod side of cylinder (7) enters into A1 por t on control valve (2) and returns into the tank through bucket valve.

Bucket Dumping Operating Circuit (1)Pilot Circuit 1. Bucket Spool Shifting When the operating lever is moved to bucket dumping position, the pilot secondary pressure oil is supplied from pilot valve (11), and enters into Pa1 port on control valve (2) to shift the bucket valve spool.

(2)Main Circuit 1. Supply Circuit for Cylinder (7) Similar to the case for bucket digging, the pressurized oil delivered from A1 port on variable pump enters into P1 port on control valve (2).

The oil supplied from A1 port through bucket valve is entered into the rod side of bucket cylinder (7) to activate the bucket dumping.

1-12

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 5

GRAPHIC_1D

BUCKET CIRCUIT: BUCKET DIGGING OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-13

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Boom Operating Circuit Pilot oil hydraulic system with operating lever Boom UP Operating Circuit (1)Pilot Circuit 1. Boom Spool Shifting When the operating lever is put at boom up position, the pilot secondary pressure oil is generated from pilot valve (11). The pressurized oil entered into Pb2 port on control valve (2) shifts the boom valve spool.

(2)Main Circuit 1. Supply Circuit for Cylinder (5) The oil delivered from A1 port on variable pump of pump assy (1) enters into P1 port on control valve (2). The oil supplied from B2 port through boom valve and lock valve is entered into the head side of boom cylinder (5) to up the boom.

Boom Down Operating Circuit (1)Pilot Circuit 1. Boom Spool Shifting When the operating lever is put at boom down position, the pilot secondary pressure oil is generated from pilot valve (11), and enters into Pa2 port on control valve (2) to shift the boom valve spool.

At the same time, the pilot secondary pressure is led to the boom lock valve (206) to push up the check valve and open the oil path from closed condition.

(2)Main Circuit 1. Supply Circuit for Cylinder (5) and Return Oil Circuit The pressurized oil delivered from A1 port on variable pump is led to boom valve provided on control valve (2), and supplied to the rod side of boom cylinder (5) to down the boom.

The oil returned from the head side of cylinder (5) enters into B2 port on control valve (2), and returns to the tank through the boom lock valve (206) and boom valve.

Its flow rate is restricted by the throttle effect in boom valve, accordingly the boom is lowered at a stable speed.

A. Boom lock valve (206) This is of a check valve mechanism to prevent the boom from lowering due to its own weight while the boom valve is being at neutral position.

1-14

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 6

GRAPHIC_1D

BOOM CIRCUIT: BOOM UP OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-15

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Arm Operating Circuit Pilot oil system with operating lever With oil flow conflux function for the third pump.

Arm In Operating Circuit (1)Pilot Circuit 1. Shift for Arm Spool At the arm in operation, the pilot secondary pressure generated from the pilot valve (11) is led to the Pa7 port on control valve (2) to shift the arm valve spool.

Furthermore, the pilot secondary pressure acts to the PP port on timer valve (303) through the shuttle valve (15) to release the parking brake.

Since the spool of the arm valve shifts to close the pilot passage, the pressure of pilot oil thru the Pi3 port equals to the supply pressure.

Thus the pressure overcomes the spring forces of the independent travel and flow conflux valves to shift the valve spool.

(2)Main Circuit 1. Supply Circuit for Cylinder (6) The oil delivered from the A2 port on variable pump enters into P2 port on control valve (2).

The pressurized oil from the P3 port joins with the oil from the P2 port through the independent travel and flow conflux valves. The joined oil flows out from the A3 port through the arm valve and is supplied to the head side of the arm cylinder (6) to perform arm in work.

2. Return Line from Cylinder (6) The return oil from the rod side of arm cylinder enters into the B7 port on control valve(2), and is led to the return line from the T1 port through arm valve, then return to the tank.

Operating Circuit for Arm Out (1)Pilot Circuit At the operation for arm out, the pilot secondary pressure is generated from the pilot valve (11), and led to the Pb7 port on control valve (2) to shift the arm valve spool.

The independent travel and flow conflux valves are actuated as in the excavating operation.

(2)Main Circuit As in the case of excavating operation, the oil having flown into the control valve (2) joins with the pressurized oil from P2 and P3, flows out from the B7 port and is supplied to the rod side of the arm cylinder to perform arm out work.

1-16

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 7

GRAPHIC_1D

ARM CIRCUIT: ARM IN OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-17

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Swing Operating Circuit Cable driving system with operating pedal Swing (left) Operating Circuit (1)Swing Operation The pilot secondary pressure oil is discharged from pilot valve (11) by the left swing operation.

The pressure oil flows into Pa5 port on the control valve (2) through solenoid valve (21), and changes the swing valve spool.

1. Operate the swing lever regularly, leaving the switch on the upper part of the left control lever pressed, the function of pilot line for slewing changes to swing function while solenoid valve (21) is actuated, and the swing operation starts.

If this switch is released, swing operation is continued till the left control lever is placed in neutral position.

When returning left control lever to neutral position, solenoid valve (21) changes to former state and pilot control line returns to slewing circuit.

(2)Main Circuit 1. Supply Circuit for Cylinder (8) The delivered oil from A2 port on variable pump enters into P2 port on control valve (2), and comes out from A5 port through cylinder valve, and is supplied to the head side of cylinder (8) to activate the swing (left).

A. At activation of the swing valve spool for both left an d r ight swing m otio ns, a par t o f appropriate volume of oil is returned to the tank through the P2 bypass circuit due to the throttle effect on the spool.

Then supplying volume of oil to the cylinder is restricted to ensure the slow and stable swing motions for both leftward and rightward.

1-18

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 8

GRAPHIC_1D

SWING CIRCUIT: BOOM SWING LEFT OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-19

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Dozer Operating Circuit Pilot oil system with operating lever Dozer Down Operating Circuit (1)Dozer Operation When the operating lever is pushed forward, the pilot secondary pressure is generated from the pilot valve (14) to shift the dozer valve spool through the Pb9 port of the control valve (2).

(2)Main Circuit 1. Supply Circuit for Cylinder (9) The oil delivered from A3 port of the hydraulic pump (1) enters into P3 port on control valve (2), and is led to B9 port through dozer valve. The pressurized oil passed through swivel joint (10) is supplied to the head side of dozer cylinder (9) to activate dozer down motion.

1-20

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 9

GRAPHIC_1D

DOZER CIRCUIT: DOZER DOWN OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-21

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Nibbler & Breaker Operating Circuit Pilot oil hydraulic system with operating pedal.

Nibbler Close Circuit (1)Pilot Circuit Press the red colored "Close" button on the left operation lever, and secondary pilot pressure flows out from A port of solenoid valve (24).

The pressurized oil which entered into Pb6 port of control valve (2) switches the spool for Nibbler/ Breaker.

(2)Main Circuit 1. Supply Circuit for Nibbler Cylinder The delivery oil from the A2 port of the 2nd pump of pump assy (1) flows in the P2 port of control valve (2) and is fed in the B6 port through nibbler/ breaker valve. And it is fed in the H side of the nibbler cylinder and consequently the nibbler "close" operation is executed.

(2)Main Circuit 1. Supply Circuit for Breaker The delivery oil from the A2 port of the 2nd pump of pump assy (1) flows in the P2 port of control valve (2) and is fed in the A4 port through nibbler/ breaker valve. And is fed in the breaker inlet and the breaker starts operating. Then, selector valve (23) of the return circuit is switched to the breaker side, consequently the return oil return in hydraulic oil tank (26) directly.

2. Return Line from Breaker The return oil of Breaker flows thru the selector valve (23), and the oil returns directly to hydraulic tank.

2. Return Line from Nibbler Cylinder The return oil from Nibbler cylinder enters into A4 port on control valve (2), and flows into return path thru the service valve, and then returns from T2 port to the hydraulic tank.

Nibbler Open Operating Circuit (1)Pilot Circuit Press the white colored "Open" button on the left operation lever, and secondary pilot pressure flows out from B port of solenoid valve (24).

The pressurized oil which entered into Pa6 port of control valve (2) switches the spool for Nibbler/ Breaker.

(2)Main Circuit The pressurized oil is flowed in the control valve (2) together, and it is same operation as closing circuit.

The confluent oil flows from A4 port, enters into R side of Nibbler cylinder, and opens the Nibbler.

Breaker Blow Circuit Change the valve position of selector valve (23) to the position for Breaker.

(1)Pilot Circuit Press the white colored "Open" button on the left operation lever, and secondary pilot pressure flows out from B port of solenoid valve (24).

The pressurized oil which entered into Pa6 port of control valve (2) switches the spool for Nibbler/ Breaker.

1-22

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 10

GRAPHIC_1D

NIBBLER & BREAKER CIRCUIT: NIBBLER CLOSE OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-23

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Travel / Dozer Combined Operating Circuit At the combined operation of travel and dozer at the same time, the straight traveling is secured with this function.

Travel (1st speed forwarding) /Dozer Down Operating Circuit (1)Pilot Circuit Both the travel and dozer are operated by the lever using the pilot oil system.

The operation of each lever directly shifts the travel valve spool and dozer valve spool in the control valve (2) respectively.

(2)Main Circuit The oil delivered from A1 and A2 ports on the variable pump (1) enters into P1 and P2 ports on control valve (2), and each flow of left and right is led to swivel joint (10) and travel motor (4) respectively through each travel valve of left and right.

The oil delivered from A3 port on the third pump enters into P3 port on control valve (2), then it is led to the dozer cylinder (9) through dozer valve and swivel joint (10).

1. The dozer is operated by the pressurized oil supplied by the third pump which has no relation with travel circuit. Then there is no variation on the supply volume of pressurized oil for both travel motors of left and right even though the dozer is operated during traveling.

Thus the straight traveling is secured.

(The slewing is operated in the same way as the dozer.)

2. As the above mentioned, the traveling speed is not changed from the single operation for traveling securing the straight traveling.

1-24

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 11

GRAPHIC_1D

COMBINED OPERATION CIRCUIT: TRAVEL (FORWARD) 1ST SPEED/ DOZER DOWN OPERATON 5-16090 EN-US

Issued 01-2008

Bur

1-25

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

Travel / Boom Combined Operating Circuit At the combined operation of travel and boom at the same time, the straight traveling is secured with this function.

Travel (1st Speed Forward) / Boom Up Operating Circuit (1)Pilot Circuit The traveling/boom up is of the pilot oil hydraulic system with lever operation.

By means of pushing forward of travel operating lever and pulling this side of boom up operating lever, the pilot secondary pressure shifts the travel valve spool and/or boom spool in the control valve (2).

Thus the pilot passage of the boom valve is closed to make the pressure of the oil from the Pi3 port equal to the supply pressure. Therefore the hydraulic pressure overcomes the spring force of the independent travel and flow conflux valves to shift the valve spool.

(2)Main Circuit The oil delivered from A1 and A2 ports on the variable pump enters into P1 and P2 ports on the control valve (2).

The whole amount of oil from the P1 and P2 ports is supplied to the travel motor in the same way as operating the independent travel. The oil flows from the travel valve through the B3 and B4 ports and the swivel joint (10) to the right and left travel motor (4).

The oil delivered from the port A3 of the hydraulic pump (1) is supplied to the boom cylinder. The oil through the P3 port of the control valve (2) flows through the dozer and slewing valves and through the shifted independent travel and flow conflux valves to the boom valve.

The oil from the B2 port through the boom and block valves is supplied to the head side of the boom cylinder (5).

1. When the travel and other attachments (boom, arm, bucket, swing, and service (for N & B) are o perated in com bination, the independent travel and flow conflux valves are actuated. Thus the attachments are actuated only by oil supplied from the P3 port.

Therefore the oil of the P1 and P2 ports is utilized only by the travel to secure stable travel in the combined operation.

1-26

Issued 01-2008

Bur

5-16090 EN-US

SECTION 3 - SYSTEMS

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

401

CHAPTER 1 - HYDRAULIC SYSTEM

9

4

404

406

407

407

404

3

5

408

408

403

406

401

403

402

405

405

6

402

302

23

407

407

22

15

7 10

1

21.0MPa

304

21.0MPa 304

303

305

8

305

21 20 (50 psi)

2

(22psi)

18 17

26

16 11

11

202 21.2MPa MRV3

201 22.5MPa MRV2

203 27.5MPa 25.5MPa 204

203 27.5MPa

204 25.5MPa

201 22.5MPa MRV1

204 25.5MPa

204 25.5MPa 204 25.5MPa

204 25.5MPa

12

25

13 13-1

No.

19

14 24

3.5MPa

NAME

PRESSURE:MPa {psi} No.

NAME

PRESSURE:MPa {psi}

204 OVER LOAD RELIEF VALVE

25.5 {3700}

21.2 {3074}

304 SLEW RELIEF VALVE

18.5 {2680}

27.5 {4000}

13-1 PILOT RELIEF VALVE

3.5 {508}

201 MAIN RELIEF VALVE P1,P2

22.5 {3263}

202 MAIN RELIEF VALVE P3 203 OVER LOAD RELIEF VALVE

Figure 12

GRAPHIC_1D

COMBINED OPERATION CIRCUIT: TRAVEL (FORWARD) 1ST SPEED/ BOOM UP OPERATION 5-16090 EN-US

Issued 01-2008

Bur

1-27

SECTION 3 - SYSTEMS

CHAPTER 1 - HYDRAULIC SYSTEM

NOTES

1-28

Issued 01-2008

Bur

5-16090 EN-US

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