The document provides instructions for removing and disassembling the swing reduction gearbox on an excavator model. Key steps include: 1. Shutting down the engine, relieving hydraulic pressure, and disconnecting electrical and hydraulic connections. 2. Removing 12 bolts to detach the swing reduction gearbox assembly from the frame. 3. Disassembling the gearbox by removing the cover, sun gear, planetary gears, shafts, and seals. 4. Cleaning and inspecting individual parts prior to reassembly of the swing reduction gearbox.

1. K1009684E Shop Manual
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
K1009684E
Serial Number 5001 and Up
DX340LC

2. Table of Contents
Page I
1Table of Contents
Safety
Track Excavator Safety......................................................................... SP000014
Specifications
Specification for DX340LC.................................................................... SP000244
General Maintenance
General Maintenance Procedures........................................................ SP000016
Standard Torques................................................................................. SP000017
Upper Structure
Cabin .................................................................................................... SP000018
Counterweight....................................................................................... SP000019
Fuel Tank.............................................................................................. SP000277
Swing Bearing....................................................................................... SP000022
Swing Reduction Gear.......................................................................... SP000249
Lower Structure and Chassis
Track Assembly .................................................................................... SP000024
Air Conditioner...................................................................................... SP000025
Engine and Drive Train
Drive Coupling (Main Pump)................................................................. SP000026
Hydraulics
Hydraulic System Troubleshooting, Testing and Adjustment ............... SP000276
Accumulator.......................................................................................... SP000028
Center Joint (Swivel)............................................................................. SP000181
Cylinders............................................................................................... SP000030

3. Table of Contents
Page II
Swing Motor.......................................................................................... SP000261
Travel Motor.......................................................................................... SP000253
Main Pump............................................................................................ SP000278
Gear Pump ........................................................................................... SP000260
Main Control Valve ............................................................................... SP000034
Remote Control Valve (Work Lever / Joystick)..................................... SP000069
Travel Control Valve (With Damper)..................................................... SP000070
Breaker EPPR Valve (Opt) ................................................................... SP000192
Hydraulic Schematic (DX340LC).......................................................... SP000259
Electrical System
Electrical System .................................................................................. SP000038
Electrical Schematic (DX300LC/340LC)............................................... SP000039
Attachments
Boom and Arm...................................................................................... SP000040
Bucket................................................................................................... SP000041

4. SP000014
Page 1
Track Excavator Safety
SP000014
TRACK EXCAVATOR SAFETYSP000014
Track
Excavator
Safety
Edition 1

5. Track Excavator Safety
Page 5
SP000014
SAFETY PRECAUTIONS
APPLICABLE MODELS
The contents of this section apply to the following models and
serial number ranges.
CAUTION!
Follow all safety recommendations and safe shop practices
outlined in the front of this manual or those contained
within this section.
Always use tools and equipment that are in good working
order.
Use lifting and hoisting equipment capable of safely
handling load.
Remember, that ultimately safety is your own personal
responsibility.
MODEL SERIAL NUMBER RANGE
DX300LC 5001 and Up
DX340LC 5001 and Up

6. SP000014Track Excavator Safety
Page 6
TO THE OPERATOR OF A
DOOSAN DAEWOO EXCAVATOR
Please respect the importance of taking responsibility for your
own safety, and that of other people who may be affected by
your actions.
The safety information on the following pages is organized into
the following sections:
1. “General Safety Essentials” on page 1-10
2. “Location of Safety Labels” on page 1-11
3. “Summary of Safety Precautions for Lifting in Digging
Mode” on page 1-12
4. “Unauthorized Modifications” on page 1-13
5. “General Hazard Information” on page 1-13
6. “Before Starting Engine” on page 1-22
7. “Machine Operation” on page 1-26
8. “Maintenance” on page 1-33
9. “Battery” on page 1-42
10. “Towing” on page 1-44
11. “Shipping and Transportation” on page 1-45
12. “Lifting With Sling” on page 1-45
DANGER!
Unsafe use of the excavator could lead to serious injury or
death. Operating procedures, maintenance and equipment
practices or traveling or shipping methods that do not
follow the safety guidelines on the following pages could
cause serious, potentially fatal injuries or extensive
damage to the machine or nearby property.

7. Track Excavator Safety
Page 7
SP000014
WARNING!
Improper operation and maintenance of this machine can
be hazardous and could result in serious injury or death.
Operator and maintenance personnel should read this
manual thoroughly before beginning operation or
maintenance.
Keep this manual in the storage compartment to the rear of
the operator's seat, and have all personnel involved in
working on the machine read the manual periodically.
Some actions involved in operation and maintenance of the
machine can cause a serious accident, if they are not done
in a manner described in this manual.
The procedures and precautions given in this manual apply
only to intended uses of the machine.
If you use your machine for any unintended uses that are
not specifically prohibited, you must be sure that it is safe
for any others. In no event should you or others engage in
prohibited uses or actions as described in this manual.
DOOSAN delivers machines that comply with all applicable
regulations and standards of the country to which it has
been shipped. If this machine has been purchased in
another country or purchased from someone in another
country, it may lack certain safety devices and
specifications that are necessary for use in your country. If
there is any question about whether your product complies
with the applicable standards and regulations of your
country, consult DOOSAN or your DOOSAN distributor
before operating the machine.

8. SP000014Track Excavator Safety
Page 8
Learn the Signal Words Used with the
Safety Alert Symbol
The words "CAUTION," "WARNING," and "DANGER" used
throughout this manual and on decals on the machine indicate
degree of risk of hazards or unsafe practices. All three degrees
of risk indicate that safety is involved. Observe precautions
indicated whenever you see the Safety Alert "Triangle," no
matter which signal word appears next to the "Exclamation
Point" symbol.
SAFETY ALERT SYMBOL
Be Prepared - Get to Know All Operating and Safety
Instructions.
This is the Safety Alert Symbol. Wherever it appears in this
manual or on safety signs on the machine you should be
alert to the potential for personal injury or accidents.
Always observe safety precautions and follow
recommended procedures.
CAUTION!
This word is used on safety messages and safety labels and
indicates potential of a hazardous situation that, if not
avoided, could result in minor or moderate injury. It may
also be used to alert against a generally unsafe practice.
WARNING!
This word is used on safety messages and safety labels and
indicates potential of a hazardous situation that, if not
avoided, could result in serious injury or death. It may also
be used to alert against a highly unsafe practice.
DANGER!
This word is used on safety messages and safety labels and
indicates an imminent hazard of a situation that, if not
avoided, is very likely to cause death or extremely serious
injury. It may also be used to alert against equipment that
may explode or detonate if handled or treated carelessly.

9. Track Excavator Safety
Page 9
SP000014
Safety precautions are described in SAFETY from page -11 on.
DOOSAN cannot predict every circumstance that might involve
a potential hazard in operation and maintenance. Therefore the
safety messages in this manual and on the machine may not
include all possible safety precautions. If any procedures or
actions not specifically recommended or allowed in this manual
are used, you must be sure that you and others can do such
procedures and actions safely and without damaging the
machine. If you are unsure about the safety of some procedures,
contact a DOOSAN distributor.

10. SP000014Track Excavator Safety
Page 10
GENERAL SAFETY ESSENTIALS
Accessory Applications
The excavator has been primarily designed for moving earth
with a bucket. For use as a grapple or for other object handling,
contact DOOSAN for proper installation and application. Lifting-
work applications (unless restricted or prohibited by local
regulations) are permitted in approved lift configuration, to rated
capacity only, with no side-loading. DO NOT use the machine for
activities for which it was not intended. DO NOT use the bucket
for lifting work, unless lift slings are used in the approved
configuration.
Use of an accessory hydraulic hammer (breaker), work in rough
terrain, demolition applications or other hazardous operation
may require installation of additional protective structures to
safeguard the operator.
Lifting Capacity Rating Configuration
Lifting capacity ratings that are printed at the end of this safety
section are based on the machine being level, on a firm
supporting surface, with hooks and slings attached in approved
configuration. Loads must be balanced and supported evenly.
Use tag lines to keep the load steady if wind conditions and
large surface area are a problem. Work crew hand signals,
individual tasks and safe procedures should all be universally
understood before the lift is made.
IMPORTANT
Before using the excavator to make lifts check municipal
and regional regulations or statutes that could apply.
Governing ordinances may require that all heavy lifting be
done with single purpose equipment specifically designed
for making lifts, or other local restrictions may apply.
Making heavy lifts with a general purpose excavator that
can be used for digging, loading, grading or other work may
be expressly forbidden by a regional injunction or other
legal prohibition. Always follow all of the other instructions,
guidelines and restrictions for Safe Lifting in the Operation
and Maintenance Manuals.

11. SP000249
Page 1
Swing Reduction Gear
SP000249
SWING REDUCTION GEARSP000249
Swing
Reduction Gear
Edition 1

12. SP000249Swing Reduction Gear
Page 12
REMOVAL
1. Park on firm and level ground.
2. Lower front attachment (bucket) to ground.
3. Shut down engine.
4. Set safety lever on "RELEASED" position.
5. Turn starter switch to "I" (ON) position.
6. Fully stroke work levers (joysticks) in all directions to
relieve any pressure from accumulators.
7. Set safety lever on "LOCK" position.
8. Turn key to "O" (OFF) position and remove from starter
switch.
9. Hang a maintenance warning tag on controls.
10. Disconnect negative (-) battery cable leading to frame from
battery.
11. Tag and disconnect hoses from swing motor (1, Figure 3).
Plug and cap hoses and ports to prevent contamination
from entering hydraulic system or component.
12. Disconnect tube (2) from drain cock (3) and hose fitting (7)
from fill hole.
13. Remove twelve bolts and washers (4, Figure 3) holding
swing reduction gearbox (5) to frame.
14. Using a suitable lifting device, sling swing motor (1, Figure
3) and remove swing motor and reduction gearbox (5) as
an assembly from unit.
NOTE: A drain cock (3, Figure 3) and tube are on side
of gearbox. Be careful not to damage valve or
tube.
NOTE: There are two alignment pins (6, Figure 3), one
on each side of reduction gearbox flange.
O I
FG003015
WARNINGWARNING
DON'T TOUCH WHEN
PERFORMING INSPECTION
OR MAINTENANCE
Figure 2
WARNING!
If engine must be running while performing
maintenance, always use extreme caution. Always
have one person in cab at all times. Never leave cab
with engine running.
Figure 3

13. Swing Reduction Gear
Page 13
SP000249
DISASSEMBLY
NOTE: Clean all exterior surfaces of the gearbox before
beginning disassembly.
1. Remove the drain plugs and allow all oil to drain from the
gearbox.
2. Remove the socket cap screws that hold the cover to the
gearbox housing. Remove the cover from the housing.
3. Remove the sun gear.
4. Thread an eye bolt into each of the three shafts that
support the 1st level planetary gears. Loop lifting straps
through the eye bolts and lift the planetary gears and the
first planetary mounting plate out of the gearbox.
5. Slide sun gear off the shaft and out of the gearbox.
6. Thread an eye bolt into each of the three shafts that
support the planetary gears. Loop lifting straps through the
eye bolts and lift the gear housing assembly out of the
gearbox.
Figure 4
IMPORTANT
Use a clean, dry container (with at least 11 liters, or 2.9
gallons capacity) to catch gear oil. A clean container
allows an evaluation to be made of the used oil. The
presence or relative lack of metal wear shavings in the
used oil or obvious deterioration or contamination of
the oil can provide a useful indicator of the motor’s
general condition.
Figure 5
Figure 6

14. SP000249Swing Reduction Gear
Page 14
7. Use a flat tipped punch to drive the spring pin back into the
shaft, so that the shaft can be pulled out of the gear
housing. Drive back the spring pins on the other two shafts.
8. Hold the planetary gear and thrust plate with one hand and
slide the gear shaft out of the housing. Use this method to
remove the two remaining gear shafts, gears, and thrust
plates.
Use the punch to drive the spring pins out of the shafts.
Use new spring pins when assembling the gearbox.
9. Sealant has been applied to the joint where the ring gear
and the gear case meet. It will be necessary to pry the ring
gear from the gear case, to separate the two parts.
10. Use a screwdriver to pry the snap ring from the output side
of the gear case.
Figure 7
Figure 8
Figure 9
Figure 10

15. Swing Reduction Gear
Page 15
SP000249
11. Insert the gear case into a hydraulic press. Position the
gear case so that the input end of the shaft is facing up.
Insert a metal spacer into the bore of the shaft. Press down
on the shaft until the shaft, with the spacer, plate, and roller
bearing attached, is pressed out of the gear case.
12. Reach into the gear case and remove the roller bearing.
13. Use a hammer and a screwdriver to drive the seal out of
the gear case.
NOTE: It is only necessary to disassemble the shaft
when one of the shaft components is damaged
(bearing, spacer, etc.) and needs replacement.
Figure 11
Figure 12
Figure 13

16. SP000249Swing Reduction Gear
Page 16
14. Set the shaft down into a metal pipe that has an inside
diameter of 145 mm. The pipe should contact the bearing
inner race only. Place a metal spacer on top of the shaft.
Use a hydraulic press to press down on the spacer until the
bearing is free of the shaft. Slide the shaft spacer, plate,
bearing and bearing spacer off the shaft.
15. Use a nonflammable, nontoxic solvent to clean all gearbox
parts. Dry the parts with compressed air. Inspect all parts
before assembly. Replace any parts that show damage or
obvious signs of wear.
Figure 14

17. Swing Reduction Gear
Page 17
SP000249
ASSEMBLY
Shaft and S/R Bearing Shrinkage Fitting
1. Washing of the shaft
Remove liquid like anti-corrosion liquid on the shaft and
then use an air gun to remove all of remaining foreign
substance.
2. Insert the spacer in the prepared shaft as shown in the
figure below and put and heat the bearing on the specified
heater.
Figure 15
Figure 16

18. SP000249Swing Reduction Gear
Page 18
3. Lift the bearing when the temperature of the heater
reaches 90° - 100°C (194° - 212°F) and put it into the shaft
with both hands holding it horizontally. To do so, insert it
slowly about 4 to 5 mm that the bearing takes its seat by
itself and then push it with force that it sticks to the spacer
assembled into the shaft.
Figure 17
Figure 18

19. Swing Reduction Gear
Page 19
SP000249
4. After completing the assembly of the bearing, allow the
bearing to air dry for one to two hours.
Assembly of the Carrier Subassembly
Washing of the Carrier
Use a dipping washer to wash the carrier which was got rid of
burr through a corner end finishing (shaping) process, check
again if foreign substance is removed completely, and put it on
the assembly die.
Washing of Planet Gears
Check if planet gears are washed well and have any dent and
put them on the assembly die.
Figure 19
Figure 20

20. SP000249Swing Reduction Gear
Page 20
Assembly of the Carrier Subassembly 1
1. Put the carrier No.1 on the assembly jig as shown in the
figure below.
2. Put the pin assembly No.1 on the pin hole correctly and
insert it with a press.
Figure 21
Figure 22
Figure 23

21. Swing Reduction Gear
Page 21
SP000249
3. After its pressure insert, check its state visually.
4. Insert the pin assembly 1 in the 3 remaining parts with a
pressure in the same way.
5. Turn over the carrier in which the pin is inserted and put the
thrust washer No.1 on 4 pins as shown in the figure below.
Figure 24
Figure 25
Figure 26

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23. SP000249Swing Reduction Gear
Page 22
6. Assemble the planetary gear No.1.
7. Put thrust washer No.3 as shown in the figure below.
Figure 27
Figure 28
Figure 29

24. Swing Reduction Gear
Page 23
SP000249
8. Engage the snap ring (for φ 40 axis) to each thread of the
pin 1 and turn the gear to check if it rotates smooth.
Assembly of the Carrier Subassembly 2
1. Put the carrier No.2 on the assembly die as shown in the
figure below.
Figure 30
Figure 31
Figure 32

25. SP000249Swing Reduction Gear
Page 24
2. Insert the bush No.2 in the planetary gear No.2 and put the
thrust washer No.2 on it.
3. Hold the gear with both hands and the thrust washer facing
downward, insert it in the carrier, and arrange both gauges
of the carrier and the bush.
Figure 33
Figure 34
Figure 35
Figure 36