This document provides assembly and disassembly instructions for a swing motor used in excavators. It begins with general safety cautions and cleaning instructions. The disassembly process is described in 15 steps, including removing covers, plates, seals, and internal components. The reassembly process is described in 31 steps, covering the assembly of the cylinder block, rear cover, valves, seals, and installation into the motor housing. Torque specifications are provided for securing components.

1. K1006409AE Shop Manual
Copyright 2008 DOOSAN
DOOSAN reserves the right to improve our products in a continuing process to provide the best possible
product to the market place. These improvements can be implemented at any time with no obligation to
change materials on previously sold products. It is recommended that consumers periodically contact their
distributors for recent documentation on purchased equipment.
This documentation may include attachments and optional equipment that is not available in your
machine's package. Please call your distributor for additional items that you may require.
Illustrations used throughout this manual are used only as a representation of the actual piece of
equipment, and may vary from the actual item.
Shop Manual
K1006409AE
Serial Number 7440 and Up
DX300LC

2. Table of Contents
Page I
1Table of Contents
Safety
Track Excavator Safety......................................................................... SP000907
Specifications
Specification for DX300LC.................................................................... SP001747
General Maintenance
General Maintenance Procedures........................................................ SP000016
Standard Torques................................................................................. SP000813
Upper Structure
Cabin .................................................................................................... SP001737
Counterweight....................................................................................... SP001748
Fuel Tank.............................................................................................. SP001749
Fuel Transfer Pump (Opt)..................................................................... SP000021
Swing Bearing....................................................................................... SP001856
Swing Reduction Gear.......................................................................... SP001750
Lower Structure and Chassis
Track Assembly .................................................................................... SP001741
Engine and Drive Train
Drive Coupling (Main Pump)................................................................. SP000026
Hydraulics
Hydraulic System Troubleshooting, Testing and Adjustment ............... SP001751
Accumulator.......................................................................................... SP000028
Center Joint (Swivel)............................................................................. SP001620
Cylinders............................................................................................... SP000030

3. Table of Contents
Page II
Swing Motor.......................................................................................... SP000031
Travel Motor.......................................................................................... SP000032
Travel Reduction Gear.......................................................................... SP000071
Axial Piston Pump................................................................................. SP000068
Gear Pump ........................................................................................... SP000033
Main Control Valve ............................................................................... SP000034
Remote Control Valve (Work Lever / Joystick)..................................... SP000069
Travel Control Valve (With Damper)..................................................... SP001743
Solenoid Valve Assembly ..................................................................... SP001622
Breaker EPPR Valve (Opt) ................................................................... SP000192
Hydraulic Schematic (DX300LC).......................................................... SP001752
Electrical System
Electrical System .................................................................................. SP001753
Electrical Schematic DX300/340/350LC............................................... SP001768
Attachments
Boom and Arm...................................................................................... SP001851
Bucket................................................................................................... SP001852

4. SP000031Swing Motor
Page 16
DISASSEMBLY
General Cautions
1. Prepare for a clean place for disassembly. Place a rubber
sheet on place to prevent any damage to parts.
2. Wash out dust and foreign substance in motor and
deceleration assembly.
3. Take care not to damage connecting parts and ways of O-
ring, oil seal, seal surface, gear, pin, and surface of
bearings.
4. Numbers in parentheses indicate those on sectional plans
of motor.
Disassembly
1. Remove hex socket head bolt and disassemble time delay
valve assembly, beginning with rear cover (19).
FG000682
Figure 10
FG000683
Figure 11

5. SP000031
Page 17
Swing Motor
2. Remove rear cover from body (1) by removing hex socket
head bolt (23) of its assembly with impact.
3. Remove brake piston assembly from body (1) using jig.
FG000685
Figure 12
FG000686
Figure 13
FG000687
Figure 14
FG000688
Figure 15

6. SP000031Swing Motor
Page 18
4. Remove cylinder block assembly, friction plate (14), and
plate (15) from body (1).
NOTE: Pay attention to order of plates and friction
plates.
5. Remove O-ring (38) from body (1).
6. Remove shoe plate (8) from body (1) using jig.
FG000689
Figure 16
FG000690
Figure 17
FG000691
Figure 18
FG000692
Figure 19

7. SP000031
Page 19
Swing Motor
7. Remove retaining ring (4) from body (1) using retaining
ring pliers.
8. Turn body over, and separate shaft assembly using steel
bar.
9. Separate piston assembly (13) from cylinder block
assembly.
FG000693
Figure 20
FG000694
Figure 21
FG000695
Figure 22
FG000696
Figure 23

8. SP000031Swing Motor
Page 20
10. Remove friction plate (12), plate (15), ball guide (11), and
spring (10) from cylinder block.
FG000697
Figure 24
FG000698
Figure 25
FG000699
Figure 26
FG000700
Figure 27

9. SP000031
Page 21
Swing Motor
11. Separate valve plate (22) from rear cover (19).
12. Remove O-ring (17) from rear cover (19).
FG000701
Figure 28
FG000703
Figure 29
FG000704
Figure 30
FG000705
Figure 31

10. SP000031Swing Motor
Page 22
13. Remove two relief valve assemblies (33) from rear cover
(19).
14. Remove check valve assemblies from rear cover (19) with
L wrench, and disassemble it in order of plug (26), spring
(23), and poppet (24).
FG000706
Figure 32
FG000707
Figure 33
FG000708
Figure 34
FG000709
Figure 35

11. SP000031
Page 23
Swing Motor
15. Remove plug (29) from rear cover (19) with L wrench and
disassemble it in order of backup ring (50), O-ring (49), O-
ring (48), spring, and anti-inversion valve assembly (28).
16. Remove plugs (36 and 37) from rear cover (19) with L
wrench
CLEANING AND INSPECTION
(WEAR LIMITS AND
TOLERANCES)
For general cleaning and inspection procedures, refer to
"General Maintenance Procedures" section.
FG000710
Figure 36
FG000711
Figure 37
FG000712
Figure 38
FG000713
Figure 39

12. SP000031Swing Motor
Page 24
REASSEMBLY
General Cautions
1. Wash and clean each part. Then dry them with
compressed air. The friction plate, however, should not be
washed with treated oil.
2. Each connecting parts should be tightened according to its
assigned torque.
3. Only use a plastic soft-faced hammer.
Assembly
1. Put roll bearing (3) and bushing (39) on a heater and apply
heat to their inner race (inlet temperature: 290°C for 2
minutes).
39
3
FG001328
Bushing X 1ea
(SUJ)
Roll Bearing X 1ea
(NUP2209)
Figure 40
FG000715
Figure 41

13. SP000031
Page 25
Swing Motor
2. Assemble heated roll bearing (3) and bushing (39). Use
retaining ring pliers to assemble install retaining ring (7).
3. Put body (1) on assembly jig and secure it so it cannot
move.
4. Assemble oil seal (2) in body (1) using bar hammer.
FG000716
Figure 42
FG000717
Figure 43
FG000718
Figure 44
FG000719
Figure 45

14. SP000031Swing Motor
Page 26
5. Install shaft in body (1) using bar hammer.
6. Secure shaft with retaining ring (4) using retaining ring
pliers.
FG000720
Figure 46
FG000717
Figure 47
FG000721
Figure 48
FG000722
Figure 49

15. SP000031
Page 27
Swing Motor
7. Coat shoe plate (8) with grease, and assemble it into body.
Assembly of Cylinder Block Assembly
Subassembly
8. Insert nine sets of springs (1 thru 9) in cylinder block (9).
FG000723
Figure 50
FG000724
Figure 51
FG000725
Figure 52
FG000726
Figure 53

16. SP000031Swing Motor
Page 28
9. Insert ball guide (1-B-11) in cylinder block (9).
10. Assemble friction plate (14) and plate (15) into cylinder
block (9)
FG000727
Figure 54
FG000728
Figure 55
FG000729
Figure 56
FG000759
Figure 57

17. SP000031
Page 29
Swing Motor
11. Insert piston assembly (1-C-13) in set plate (1-B-12) and
assemble it into cylinder block (9).
NOTE: Coat piston with clean hydraulic oil.
FG000730
Figure 58
FG000731
Figure 59
FG000696
Figure 60
FG000732
Figure 61

18. SP000031Swing Motor
Page 30
12. Assemble cylinder block into body (1).
13. Insert O-ring (38) in body (1).
14. Assemble O-ring (17) into brake piston (16).
FG000733
Figure 62
FG000734
Figure 63
FG000704
Figure 64
FG000687
Figure 65

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20. SP000031
Page 31
Swing Motor
15. Insert brake piston assembly in body and secure it using
jig.
16. Insert eighteen springs (18) into brake piston (16).
Assembly of Rear Cover Assembly
Subassembly
1. Insert pins (6 and 21) in rear cover (19) with bar hammer
and assemble needle bearing (20) using jig.
FG000735
Figure 66
FG000736
Figure 67
FG000737
Figure 68
FG000738
Figure 69

21. SP000031Swing Motor
Page 32
2. Assemble O-ring (17) into rear cover (19).
3. Assemble check valve. Install O-ring (27) using jig.
FG000739
Figure 70
FG000740
Figure 71
FG000741
Figure 72
FG000742
Figure 73

22. SP000031
Page 33
Swing Motor
4. Insert poppet (24), spring (25), and plug (26) in rear cover
(19). Tighten plug with L wrench. (Left and right
symmetrically.)
5. Assemble anti-inversion valve. Assemble body, spring
seat, spring, poppet, poppet seat, stopper, and spring.
Then assemble O-ring (31), backup ring (32), and O-ring
(30).
FG000743
Figure 74
FG000708
Figure 75
FG000744
Figure 76
FG000745
Figure 77