The document provides instructions for reassembling a travel motor. It describes 38 steps for reassembling the internal components and housing of the motor. Quality checks are recommended after reassembly, including an air leak test of the reduction unit and motor, and running the motor while filling it with hydraulic fluid to check for issues. Exploded views of the motor, reduction unit, and anti-cavitation valve are also included.

1. K1028288E Shop Manual
Copyright 2007 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
K1028288E
Serial Number 5001 and Up
DX27Z

2. Table of Contents
Page I
1Table of Contents
Safety
Track Excavator Safety....................................................................... SP001061
Specifications
Specification for DX27Z ...................................................................... SP001106
General Maintenance
General Maintenance Procedures ...................................................... SP000016
Standard Torques ................................................................................ SP000813
Upper Structure
Cabin .................................................................................................... SP001063
Swing Bearing...................................................................................... SP001064
Lower Structure and Chassis
Track Assembly ................................................................................... SP001099
Engine and Drive Train
Drive Coupling (Main Pump) .............................................................. SP001066
Hydraulics
Accumulator.......................................................................................... SP000028
Center Joint (Swivel)........................................................................... SP001067
Cylinders............................................................................................... SP001100
Swing Motor......................................................................................... SP001101
Travel Motor......................................................................................... SP001102
Main Pump........................................................................................... SP001103
Main Control Valve.............................................................................. SP001071
Remote Control Valve (Work Lever / Joystick) ................................ SP001072

3. Table of Contents
Page II
Travel Control Valve............................................................................ SP000839
Pedal Valve.......................................................................................... SP001073
Hydraulic Schematic (DX27Z)............................................................. SP001104
Electrical System
Electrical System ................................................................................. SP001142
Electrical Schematic (DX27Z) ............................................................. SP001144
Attachments
Working Attachments........................................................................... SP001105
Bucket................................................................................................... SP001076

4. SP001102
Page 49
Travel Motor
REASSEMBLY
Assemble the travel motor by the following procedure.
1. Apply grease to floating seal and install it on flange holder.
Tools required: Floating seal assembly jig
2. Press fit angular bearings to housing.
Tools required: Angular bearings press fitting jig
3. Apply grease to the second floating seal and place it
on the concentric circle. Install it on housing.
Tools required: Floating seal assembly jig
Figure 53
Figure 54
Figure 55

5. SP001102Travel Motor
Page 50
4. Apply lubricating oil on the sliding surface of floating
seal after make the surface clean by rags. Install
flange holder in housing .
Tools required: Flange holder press fitting jig
5. Tighten angular bearing with ring nut.
Tools required: Torque wrench
Ring nut tightener
Tightening torque 235±9.8N•m
6. Tighten plug.
The seal tape is not allowed to wrap for assembling of
this plug.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tinhtening torque 34.3±4.9N•m
7. Caulk plug two positions with punch to lock.
Tools required: Hammer
Punch
Figure 56
CAUTION!
If there are foreign articles on the sliding surface of
floating seal, it causes oil.
Figure 57
Figure 58
Figure 59

6. SP001102
Page 51
Travel Motor
8. Place steel balls (99 pcs) in.
9. Wrap plug with seal tape, and tighten it.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tightening torque 7.8±1.0 N•m
10. Install planetary gear B, needle bearing, inner race,
thrust washer.
11. Put thrust plate on the trunnion section of flange
holder, apply Loctite #262 to screw and tighten it.
Before applying the Loctite, degrease the parts
completely and us hardening accelerator.
Tools required: Torque wrench
Hexagonal bit fot torque wrench
Tighten torque 12.7±0.6N•m
Figure 60
IMPORTANT
If it is difficult to place steel balls in, beat on the
side of housing by using of plastic hammer.
Figure 61
CAUTION!
Tighten plug until the head of plug is obscured
against the surface of sprocket guide.
Figure 62
Figure 63

7. SP001102Travel Motor
Page 52
12. Instll sun gear assembly with snap ring, holder with
inner race, planetary gear A, needle bearing and drive
gear.
13. Install thrust plate.
14. Apply grease to O-ring, fit the O-ring on cover, and
install cover to housing matching the threaded hole of
socket plug of housing with the U-groove (for piano
wire).
Tools required: Plastic hammer
Eyebolt
15. Bend 6 mm of the top end of wire at right angle, insert
it into the threaded hole of the housing, and wind the
piano wire turning the cover. Wrap socket plug with
seal tape before thighening.
Tools required: Eyebolt
Round bar Dia. 20*1000 mm
Torque wrench
Hexagonal bit for torque wrench
Tightening Torque 7.8±1.0N•m
Figure 64
Figure 65
Figure 66
Figure 67

8. SP001102
Page 53
Travel Motor
16. Apply grease to oil seal and press fit it in flange
holder.
Tools required: Oil seal press fitting jig
17. Press fit ball bearing on shaft.
Tools required: Ball bearing press fitting jig
Shaft sub assembly press fitting jig
18. Press fit shaft sub assembly in flange holder.
Tools required : Shaft sub assembly press fitting jig
19. Install sreel ball, spring, piston assembly and swash
plate on flange holder. Apply hydraulic oil to the sliding
surface of the swash plate.
Figure 68
Figure 69
Figure 70
Figure 71

9. SP001102Travel Motor
Page 54
20. Install washer, spring, spring seat and snap ring on
cylinder block.
Tools required: Snap ring pliers
Snap ring assembly jig
21. Apply grease to pin, install pins in three holes of
cylinder block.
22. Install retainer holder, retainer plate and piston sub
assembly. Apply hydraulic oil in 99holes of cylinder
block.
Only parking brake type Install disk plate.
23. Place the motor laterally, and install the cylinder block
sub assembly regarding the spline of the shaft as a
guide.
Figure 72
Figure 73
Figure 74
Figure 75
IMPORTANT
Location of spline tooth of cylinder block should be
aligned that of retainer holder to install them easily.

10. SP001102
Page 55
Travel Motor
24. Push the cylinder block by hand, and check that the
spring contracts and restores. Apply hydraulic oil to the
sliding surface of the cylinder block.
25. Apply grease to O-ring, and install pin and them on
flange holder.
26. Press fit ball bearing on base plate.
Tools required: Ball bearing press fitting jig
27. Apply grease on the bake side of valve plate, and
install it and pin, o-ring on base plate.
Figure 76
CAUTION!
Confirm no foreign articles on surface of cylinder
block, marked a circle. If there are foreign articles
on it, wipe off them.
Figure 77
Figure 78
Figure 79

11. SP001102Travel Motor
Page 56
28. Apply grease to O-rings, and install them to brake
piston.
Install brake piston to flange holder to align pin
installed on base plate in with holes on brake piston.
When install it, beat on evenly outside of brake piston
by using of plastic hammer.
Tools required: Plastic hammer
29. With parking brake type-Install springs base plate, pin.
Without parking brake type- Install base plate.
Figure 80
Figure 81
CAUTION!
Each back up ring should be set out side position.
Be careful of installing direction brake piston.
Figure 82
CAUTION!
Be careful of installing assprings, don’t fall dawn.
It is difficult to fall down by greased them.
Figure 83

12. SP001102
Page 57
Travel Motor
30. Tighten socket head bolt.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tightening torque 128.5±6.9N•m
31. Place spool and spring in.
Place the spool in while turning to prevent them from
sticking.
Apply hydraulic oil to the spool before installation.
32. Tighten plugs, with O-ring.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Socket for torque wrench
Tightening torque 53.9±4.9N•m
33. Install check valve, spring and plug with O-ring to plunger.
Apply a slight grease to the O-ring.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tightening torque 31.9±2.45N•m
Figure 84
Figure 85
Figure 86
Figure 87

13. SP001102Travel Motor
Page 58
34. Install plunger assembly on base plate.
Install it while turning to prevent it from sticking.
Apply hydraulic oil to plunger assembly before
installation.
35. Place spring and spring seat in.
36. Tighten cap with O-ring.
Apply a slight grease to the O-ring.
Tools required : Torque wrench
Hexagonal bit for torque wrench
Tightening torque 240±5N•m
37. Tighten plug with O-ring and shipping plug.
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tightening torque 53.9±4.9N•m
Figure 88
Figure 89
Figure 90
Figure 91

14. SP001102
Page 59
Travel Motor
38. With parking brake type
Install spool, spring and spring seat in valve body, and
tighten plug.
Tools required : Torque wrench
Hexagonal bit for torque wrench
Tightening torque 53.9±4.9N•m
39. Fit O-rings or to valve body, and put valve assembly
on base plate.
Tighten socket head bolt .
Tools required: Torque wrench
Hexagonal bit for torque wrench
Tightening torque 36.9±1.9N•m
40. Pour the gear oil through the threaded hole of plug.
Wind the plug with seal tape before tightening.
Tools required: Torque wrench
Hexagonal bit for torque wrench
PF1/4 Tightening torque 34.3±4.9N•m
PF1/4 Tightening torque 39.2±2.0N•m
41. Completed.
Figure 92
Figure 93
Figure 94
Figure 95

15. SP001102Travel Motor
Page 60
Quality Check After Reassembly
1. Air Leak Test of Reduction Unit
Remove one plug of the reduction unit apply
compressed air (0.03 Mpa) through tapped hol of plug
in water for two mimutes, and observe that there are
no bubbles.
2. Air Leak Test of Motor
Seal all piping ports on the motor except one port with
plugs, and apply compressed air (0.03 Mpa) through
open port in water for two minutes. Observe that there
are no bubbles.
3. Upon completion of leak in subparagraphs and above,
fill the motor case with new hydraulic fluid. Run the
motor crosswise for two minutes filling hydraulic fluid at
flow rate of 20 liters per minute.
Confirm that there is no excessive heat, vibration or
noise during running.

16. SP001102
Page 61
Travel Motor
REASSEMBLY AND ASSEMBLY JIG
Figure 96

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18. SP001102Travel Motor
Page 62
Exploded View:Motor
Figure 97

19. SP001102
Page 63
Travel Motor
Exploded View:Reduction Unit
Figure 98

20. SP001102Travel Motor
Page 64
Exploded View:Anti-Cavitation Valve
Figure 99