Hyundai Excavator R450LC-7. Service and repair manual - page 8

Operating principle

When the swing control lever is operated, the swing lock solenoid valve is excited, so the pilot
pump discharged oil(P3) goes to the chamber G.
This pressure is applied to move the piston(6) to the upward against the force of the spring(9).
Thus, it releases the brake force.

2-55

②

②

a.

1

Pilot pump 

2

Swing lock solenoid valve

3

Spring

4

Brake piston 

5

Separate plate

6

Lining plate

45070SM03

2-56

1

Swing lock solenoid valve

2

Spring

3

Brake piston

4

Separate plate

5

Lining plate

When the swing control lever gets back to neutral position, the swing lock solenoid valve is
deactivated, so the pilot pump discharged oil(P

3

) is not applied to the chamber G.

Thus, the brake is actuated by spring force.  

b.

45070SM04

2-56-2

SWING MOTOR

031 Brake valve
051 Relief valve
052 Reactionless valve assy
101 Drive shaft
106 Spacer
111 Cylinder block
113 Spherical busing
114 Cylinder spring
116 Push rod
117 Spacer(F)
118 Spacer(R)
121 Piston
122 Shoe plate
123 Retainer
124 Shoe
131 Valve plate
301 Casing(F)

303 Valve casing(K)
304 Front cover
351 Plunger(K)
355 Spring
401 Socket bolt
432 Snap ring
433 Snap ring
437 Snap ring
438 Snap ring
443 Roller bearing
444 Roller bearing
451 Spring pin
464 VP Plug
468 VP Plug
469 RO Plug
471 O-ring
472 O-ring

485 O-ring
487 O-ring
488 O-ring
491 Oil seal
501 Adapter
502 Socket bolt
503

O-ring

702 Brake piston
706 O-ring
707 O-ring
712 Brake spring
742 Friction plate
744 Dust plug
745 Dust plug
746 Dust plug
993 PT Plug
994 PT Plug

702

117 121 118 114 706 707

712 472

432

106

443

471

304

101

491

437

124

301

122 123 113 116 111

742 031 743 131

451

433

745

746

487

468

303

444

106

438

994

SECTION  A - A

A

485

464

401

051

993

351 052 501

355

744

503

502

A

488

469

1)

50072SM02

2-56-3

REDUCTION GEAR

1

Casing

2

Drive shaft

3

Spacer

5

Roller bearing

6

Oil seal

7

Roller bearing

8

Thrust plate

9

Carrier 2

10

Stop ring

11

Ring gear

12

Knock pin

13

Pinion gear

14

Thrust washer

15

Planet gear 2

16

Pin 2

17

Spring pin

18

Sun gear 2

19

Carrier 1

20

Side plate 1

21

Pin 1

22

Needle cage

23

Bushing 2

24

Planet gear 1

25

Lock washer

26

Side plate 3

27

Sun gear 1

28

Stop ring

29

Plug

30

Plug

31

Socket bolt

32

Gage pipe 

33

Gage bar 

34

Cover plate

35

Hex bolt

36

Lock plate

37

Hex bolt

38

Stop ring

39

Side plate 2

25

13

37 36

20

30

1

5

35

34

3

2

23

12

14

8

17

21

16

15

10

6

29

7

18

11

9

39

27

38

22

24

26

19

31 28

32

33

2)

50072SM03

2-56-5

MAKE UP VALVE
In the system using this type of motor, there is no counter balance functioning valve and there
happens the case of revolution exceeding hydraulic supply of motor.  To prevent the cavitation
caused by insufficient oil flow there is a make up valve to fill up the oil insufficiency.
A make up valve is provided immediately before the port leading to the hydraulic oil tank to secure
feed pressure required when the hydraulic motor makes a pumping action.  The boost pressure
acts on the hydraulic motor's feed port via the make up valve.
Pressurized oil into the port B, the motor rotate counterclockwise.
If the plunger of MCV moves neutral position, the oil in the motor is drain via left relief valve, the
drain oil run into motor via right make up valve, which prevent the cavitation of motor.

2)

A

B

R130SM03

2-56-9

Brake assembly
Circumferential rotation of separate
plate(9) is constrained by the groove
located at housing(26).  When housing is
pressed down by brake spring(14)
through lining plate(10), separate
plate(9) and brake piston(12), friction
force occurs there.
Cylinder(25) is constrained by this friction
force and brake acts, while brake
releases when hydraulic force exceeds
spring force.

Mechanical swing parking brake system
The mechanical swing parking brake system is installed to prevent the upper structure from
swinging downhill because of its own weight when the excavator is parked on a slope since it
completely eliminates the hydraulic drift of swing motion while the excavator is on a slop, work can
be done more easily and safely.

BRAKE SYSTEM

Control valve swing brake system
This is the brake system to stop the swing motion of the excavator during operation.
In this system, the hydraulic circuit is throttled by the swing control valve, and the resistance
created by this throttling works as a brake force to slow down the swing motion.

4)

(1)

(2)

①

①

Work

Deceleration

Stop

MCV A, B opened

MCV A, B throttled

MCV A, B closed

MCV MCV  MCV 

A

B

A

B

A

B

9

Separate plate

10

Lining plate

12

Brake piston

14

Spring

25

Cylinder

26

Housing

R130SM05

45070SM05

2-56-10

Operating principle

When the swing control lever is operated, the swing lock solenoid valve is excited, so the pilot
pump discharged oil(P3) goes to the chamber G.
This pressure is applied to move the piston(6) to the upward against the force of the spring(9).
Thus, it releases the brake force.

②

②

a.

1

Pilot pump 

2

Swing lock solenoid valve

3

Spring

4

Brake piston 

5

Separate plate

6

Lining plate

45070SM03

2-56-11

1

Swing lock solenoid valve

2

Spring

3

Brake piston

4

Separate plate

5

Lining plate

When the swing control lever gets back to neutral position, the swing lock solenoid valve is
deactivated, so the pilot pump discharged oil(P

3

) is not applied to the chamber G.

Thus, the brake is actuated by spring force.  

b.

45070SM04