The document provides maintenance procedures for an engine, including: 1. Draining the engine oil and replacing the oil filter every 100 hours. 2. Checking and adjusting the cooling fan V-belt tension. 3. Replacing the fuel filter every 500 hours. 4. Draining the fuel filter/water separator and checking the battery every 50 hours.

1. K1038080E Shop Manual
Copyright 2007 DOOSAN
DOOSAN reserves the right to improve its products continuously, delivering the best possible product to
the marketplace. These improvements can be implemented at any time with no obligation to change
materials previously sold. It is recommended that consumers periodically contact their distributors for most
recent documentation on purchased equipment.
This documentation may include attachments and optional equipment 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
K1038080E
Serial Number 50001 and Up
DX55

2. Table of Contents
Page 1
1Table of Contents
Safety
Track Excavator Safety......................................................................... SP001478
Specifications
Specification for DX55 .......................................................................... SP001479
General Maintenance
General Maintenance Procedures........................................................ SP000016
Standard Torques................................................................................. SP000813
Upper Structure
Cabin .................................................................................................... SP001480
Swing Bearing....................................................................................... SP001551
Lower Structure and Chassis
Track Assembly .................................................................................... SP001481
Engine and Drive Train
Engine................................................................................................... SP001434
Drive Coupling (Main Pump)................................................................. SP001482
Hydraulics
Accumulator.......................................................................................... SP000028
Center Joint (Swivel)............................................................................. SP001483
Cylinders............................................................................................... SP001484
Swing Motor.......................................................................................... SP001485
Travel Motor.......................................................................................... SP001486
Main Control Valve ............................................................................... SP001487
Main Pump............................................................................................ SP001488

3. Table of Contents
Page 2
Remote Control Valve (Work Lever / Joystick)..................................... SP001489
Dozer Valve .......................................................................................... SP001490
Pedal Valve........................................................................................... SP001491
Hydraulic Schematic (DX55)................................................................. SP001492
Electrical System
Electrical System .................................................................................. SP001493
Electrical Schematic (DX55)................................................................. SP001494
Attachments
Boom and Arm...................................................................................... SP001495
Bucket................................................................................................... SP001496

4. SP001478
Page 1
Track Excavator Safety
SP001478
TRACK EXCAVATOR SAFETYSP001478
Track Excavator
Safety
Edition 1

5. SP001478
Page 5
Track Excavator Safety
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 the load.
Remember that ultimate safety is your own responsibility.
MODEL SERIAL NUMBER RANGE
DX55 50001 and Up

6. SP001478Track Excavator Safety
Page 6
TO THE OPERATOR OF A
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 1-11
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 1-41
10. “Towing” on page 1-43
11. “Shipping and Transportation” on page 1-44
12. “Lifting With Sling” on page 1-44
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. SP001478
Page 7
Track Excavator Safety
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 can
be applied 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 sent. 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. SP001478Track 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 threat 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 threat of a hazardous situation that, if
not avoided, could result in serious injury or death. It may
also be used to alert against 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 detonate or explode if handled or treated carelessly.

9. SP001478
Page 9
Track Excavator Safety
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 any procedures,
contact a DOOSAN distributor.

10. SP001434
Page 1
Engine
q SP001434
ENGINE SP001434
Engine
Edition 1

11. SP001434Engine
Page 68
The engine oil in a new engine becomes contaminated from the
initial break-in of internal parts. It is very important that the initial
oil and filter change is performed as scheduled.
NOTE: The oil drain plug may be in another location if an
optional oil pan is used.
Drain the engine oil as follows:
1. Make sure the engine is level.
2. Start the engine and bring it up to operating temperature.
3. Stop the engine.
4. Remove one of the oil filler caps (4) (1, Figure 74, Figure
75) to vent the engine crankcase and allow the engine oil
to drain more easily.
5. Position a container under the engine to collect waste oil.
6. Remove the oil drain plug (1, Figure 76) from the engine oil
pan. Allow oil to drain.
7. After all oil has been drained from the engine, reinstall the
oil drain plug (1, Figure 76) and tighten to 14 -17 ft•lb (19.6
-23.5 N•m; 2.0 -2.4 kgf•m).
8. Dispose of used oil properly.
FG009156
Figure 73
CAUTION!
Always be environmentally responsible.
Follow the guidelines of the EPA or other governmental
agencies for the proper disposal of hazardous materials
such as engine oil, diesel fuel and engine coolant. Consult
the local authorities or reclamation facility.
Never dispose of hazardous materials irresponsibly by
dumping them into a sewer, on the ground, or into ground
water or waterways.
Failure to follow these procedures may seriously harm the
environment.
Figure 74
Figure 75

12. SP001434
Page 69
Engine
Remove the engine oil filter as follows:
1. Turn the engine oil filter (2, Figure 76) counterclockwise (3,
Figure 76) using a filter wrench.
2. Clean the engine oil filter mounting face.
3. Lightly coat the gasket on the new oil filter with engine oil.
Install the new engine oil filter manually by turning it clock
wise (4, Figure 76) until it contacts the mounting surface.
Tighten an additional 3/4 of a turn using the filter wrench.
*Consult the operation manual for the driven machine for
applicability of the dust proof filter.
4. Add new engine oil to the engine as specified in Adding
Engine Oil on page 4-14.
5. Warm up the engine by running it for five minutes and
check for any engine oil leaks.
6. After engine is warm, shut it off and let it sit for 10 minutes.
7. Recheck the engine oil level.
8. Add engine oil (5, Figure 77) as needed until the level is
between the upper (2, Figure 77) and lower lines (3, Figure
77) shown on the dipstick (1, Figure 77).
9. Reinstall the oil filler cap (4, Figure 77). If any engine oil is
spilled, wipe it away with a clean cloth.
Figure 76
Engine Oil Fliter Part No.
Standard Dust proof*
4TNV98-Z 129150-35153 119005-35151
CAUTION!
Never overfill the engine with engine oil.
Always keep the oil level between the upper and lower
lines on the oil cap / dipstick.
Figure 77

13. SP001434Engine
Page 70
Check and Adjust Cooling Fan V-Belt
The V-belt will slip if it does not have the proper tension. This will
prevent the alternator from generating sufficient power. Also, the
engine will overheat due to the engine coolant pump pulley slipping.
Check and adjust the V-belt tension (deflection) as follows:
1. Press the V-belt down with your thumb with a force of
approximately 22 ft•lb (98 N•m; 10 kgf) to check the deflection.
There are three positions to check for V-belt tension (A, B
and C, Figure 78). You can check the tension at whichever
position is the most accessible. The proper deflection of a
used V-belt at each position is:
NOTE: A "Used V-Belt" refers to a V-belt which has been
used on a running engine for five minutes or more.
2. If necessary, adjust the V-belt tension. Loosen the
adjusting bolt (1, Figure 79) and move the alternator (2,
Figure 79) with a pry bar (3, Figure 79) to tighten the V-belt
to the desired tension. Then tighten the adjusting bolt.
3. Tighten the V-belt to the proper tension. There must be
clearance (1, Figure 80) between the V-belt and the bottom
of the pulley groove. If there is no clearance (2, Figure 80)
between the V-belt and the bottom of the pulley groove,
replace the V-belt.
4. Check the V-belt for cracks, oil or wear. If any of these
conditions exist, replace the V-belt.
5. Install the new V-belt. Refer to the table for proper tension.
6. After adjusting, run the engine for 5 minutes or more. Check
the tension again using the specifications for a used V-belt.
Figure 78
Used V-Belt Tension
A B C
3/8 - 1/2 in.
(10 - 14 mm)
1/4 - 3/8 in.
(7 - 10 mm)
5/16 - 1/2 in.
(9 - 13 mm)
Figure 79
1
2
FG008859
Figure 80
Used V-Belt Tension
A B C
5/16 - 7/16 in.
(8 - 12 mm)
3/16 - 5/16 in.
(5 - 8 mm)
1/4 - 7/16 in.
(7 - 11 mm)
Used V-Belt Tension
A B C
3/8 - 1/2 in.
(10 - 14 mm)
1/4 - 3/8 in.
(7 - 10 mm)
5/16 - 1/2 in.
(9 - 13 mm)

14. SP001434
Page 71
Engine
Replace Fuel Filter
HDO1015I
Figure 81
DANGER
Fire And Explosion Hazard!
Diesel fuel is flammable and explosive under certain
conditions.
When you remove any fuel system component to perform
maintenance (such as changing the fuel filter) place an
approved container under the opening to catch the fuel.
Never use a shop rag to catch the fuel. Vapors from the rag
are flammable and explosive.
Wipe up any spills immediately.
Wear eye protection. The fuel system is under pressure and
fuel could spray out when you remove any fuel system
component.
Failure to comply will result in death or serious injury.
DANGER
For maximum engine life, DOOSAN recommends that when
shutting the engine down, you allow the engine to idle,
without load, for five minutes. This will allow the engine
components that operate at high temperatures, such as the
exhaust system, to cool slightly before the engine itself is
shut down.
FG009156
Figure 82
CAUTION
Always be environmentally responsible.
Follow the guidelines of the EPA or other governmental
agencies for the proper disposal of hazardous materials
such as engine oil, diesel fuel and engine coolant. Consult
the local authorities or reclamation facility.
Never dispose of hazardous materials irresponsibly by
dumping them into a sewer, on the ground, or into ground
water or waterways.
Failure to follow these procedures may seriously harm the
environment.

15. SP001434Engine
Page 72
Replace the fuel filter at specified intervals to prevent
contaminants from adversely affecting the diesel fuel flow.
1. Stop the engine and allow it to cool.
2. Close the fuel cock of the fuel filter / water separator.
3. Remove the fuel filter with a filter wrench, turning it to the left
(1, Figure 83). When removing the fuel filter, carefully hold it
to prevent the fuel from spilling. Wipe up all spilled fuel.
4. Clean the filter mounting surface and apply a small amount
of diesel fuel to the gasket of the new fuel filter.
5. Install the new fuel filter. Turn to the right (2, Figure 83) and
hand-tighten it only until it comes in contact with the
mounting surface. Tighten to 14 - 17 ft•lb (19.6 - 23.5 N•m;
2.0 - 2.4 kgf•m) or one additional turn using the filter wrench.
6. Open the fuel cock of the fuel filter / water separator.
7. Prime the fuel system. See “Priming the Fuel System” on
page -40
8. Check for leaks.
Figure 83

16. SP001434
Page 73
Engine
Every 50 Hours of Operation
After you complete the initial 50 hour maintenance procedures,
perform the following procedures every 50 hours thereafter.
• Drain Fuel Filter / Water Separator
• Check Battery
Drain Fuel Filter / Water Separator
HDO1015I
Figure 84
DANGER!
Fire And Explosion Hazard!
Diesel fuel is flammable and explosive under certain
conditions.
When you remove any fuel system component to perform
maintenance (such as changing the fuel filter) place an
approved container under the opening to catch the fuel.
Never use a shop rag to catch the fuel. Vapors from the rag
are flammable and explosive.
Wipe up any spills immediately.
Wear eye protection. The fuel system is under pressure and
fuel could spray out when you remove any fuel system
component.
Failure to comply will result in death or serious injury.
CAUTION!
If the fuel filter / water separator is positioned higher than the
fuel level in the fuel tank, water may not drip out when the fuel
filter / water separator drain cock is opened. If this happens,
turn the air vent screw on the top of the fuel filter / water
separator 2-3 turns counterclockwise.
Be sure to tighten the air vent screw after the water has
drained out.
FG009156
Figure 85
CAUTION!
Always be environmentally responsible.
Follow the guidelines of the EPA or other governmental
agencies for the proper disposal of hazardous materials
such as engine oil, diesel fuel and engine coolant. Consult
the local authorities or reclamation facility.
Never dispose of hazardous materials irresponsibly by
dumping them into a sewer, on the ground, or into ground
water or waterways.
Failure to follow these procedures may seriously harm the
environment.

17. SP001434Engine
Page 74
Drain the fuel filter / water separator whenever there are
contaminants, such as water, collected in the bottom of the cup.
Never wait until the scheduled periodic maintenance if
contaminants are discovered.
The cup of the separator is made from semi°žtransparent
material. In the cup is a red colored float ring. The float ring will
rise to the surface of the water to show how much needs to be
drained. Also, some optional fuel filter / water separators are
equipped with a sensor to detect the amount of contaminants.
This sensor sends a signal to an indicator to alert the operator.
Drain the fuel filter / water separator as follows:
1. Position an approved container under the fuel filter / water
separator (1, Figure 86) to collect the contaminants.
2. Close (2, Figure 86) the fuel cock (3, Figure 86).
3. Loosen the drain cock (4, Figure 86) at the bottom of the
fuel filter / water separator. Drain any water collected
inside.
4. Hand-tighten the drain cock.
5. Open the fuel cock (3, Figure 86).
6. Be sure to prime the diesel fuel system when you are
finished. Priming the Fuel System on page 4-12.
7. Check for leaks.
Figure 86
CAUTION!
If the fuel filter / water separator is positioned higher
than the fuel level in the fuel tank, water may not drip
out when the fuel filter / water separator drain cock is
opened. If this happens, turn the air vent screw on the
top of the fuel filter / water separator 2-3 turns
counterclockwise.
Be sure to tighten the air vent screw after the water
has drained out.

18. SP001434
Page 75
Engine
Check Battery
Batteries in Cold Weather
In colder weather a greater drain is placed on the batteries when
they are used for the preheat cycle and when starting a cold
engine. Battery performance decreases as the temperature gets
lower.
In extremely cold weather, remove batteries at night and move
them to a warm location. This will help to keep them at a higher
power level.
WARNING
Battery electrolyte contains sulfuric acid and can quickly
burn the skin and eat holes in clothing. If you spill acid on
yourself, immediately flush the area with water.
Battery acid could cause blindness if splashed into the
eyes. If acid gets into the eyes, flush them immediately with
large quantities of water and see a doctor at once.
If you accidentally drink acid, drink a large quantity of water
or milk, beaten egg or vegetable oil. Call a doctor or poison
prevention center immediately.
When working with batteries, always wear safety glasses or
goggles.
Battery generates hydrogen gas, so there is a danger of an
explosion. Do not bring lighted cigarettes near the battery,
or do anything that will cause sparks.
Before working with batteries, shut down engine and turn
the starter switch to the "O" (OFF) position.
Avoid short-circuiting the battery terminals through acci-
dental contact with metallic objects, such as tool.
When removing or installing, check which is the positive (+)
terminal and negative (-) terminal.
When removing the battery, first disconnect the negative (-)
terminal. When installing the battery, first connect the posi-
tive (+) terminal.
If the terminals are loose, there is a danger that defective
contact may generate sparks that will cause an explosion.
When installing the terminals, install them tightly.

19. SP001434Engine
Page 76
Inspection of Battery Electrolyte Level
This machine has two maintenance free battery. It never
requires the addition to water.
When the charge indicator becomes transparent, it means low
electrolyte state because of the leakage or charging system
error. Determine the cause of problem and replace the battery
immediately.
Check Charging State
Check charging state through the charging indicator.
• GREEN: Sufficiently charged.
• BLACK: Insufficient charged.
• TRANSPARENT: Replace battery.
Check the Battery Terminals
Be certain that battery is held securely in its compartment. Clean
the battery terminals and the battery cable connectors. A
solution of baking soda and water will neutralize acid on the
battery surface, terminals, and cable connectors. Petroleum jelly
or grease can be applied to the connectors to help prevent
corrosion.
Battery Replacement
When the charging indicator indicates transparency state,
replace the battery.
FG010161
Figure 87
FG010162
Figure 88

20. SP001434
Page 77
Engine
Clean Air Cleaner Element
Note that a typical air cleaner is shown in Figure 89 and Figure
91 for illustrative purposes only.
The engine performance is adversely affected when the air
cleaner element is clogged with dust. Be sure to clean the air
filter element periodically.
1. Unlatch and remove the air cleaner cover (1, Figure 89,).
2. Remove the element (2, Figure 89) (outer element if
equipped with two elements).
3. Blow air (3, Figure 89) through the element from the inside
out using 42 -71 psi (0.29 -0.49 MPa; 3.0 -5.0 kgf/cm2)
compressed air to remove the particulates. Use the lowest
possible air pressure to remove the dust without damaging
the element.
4. If the air cleaner is equipped with a double element, only
remove and replace the inner element (1, Figure 91) if the
engine lacks power or the dust indicator actuates (if
equipped).
5. The inner element should not be removed when cleaning
or replacing the outer element. The inner element is used
to prevent dust from entering the engine while servicing the
outer element.
6. Replace the element with a new one if the element is
damaged, excessively dirty or oily.
7. Clean inside of the air cleaner cover.
8. Install the element into the air cleaner case (4, Figure 89).
9. Reinstall the air cleaner cover making sure you match the
arrow (5, Figure 89) on the cover with the arrow on the
case (6, Figure 89).
10. Latch the air cleaner cover to the case.
Figure 89
FG009152
Figure 90
CAUTION
FLYING OBJECT HAZARD!
Always wear eye protection when servicing the engine
and when using compressed air or high-pressure
water. Dust, flying debris, compressed air, pressurized
water or steam may injure your eyes.
Failure to comply may result in minor or moderate injury.
Figure 91
CAUTION
When the engine is operated in dusty conditions, clean
the air cleaner element more frequently.
Never operate the engine with the air cleaner
element(s) removed. This may allow foreign material to
enter the engine and damage it.

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22. SP001434Engine
Page 78
Every 250 Hours of Operation
Perform the following maintenance every 250 hours of
operation.
• Drain Fuel Tank
• Replace Engine Oil
• Check and Clean Radiator Fins
• Check and Adjust Cooling Fan V-Belt
Drain Fuel Tank
HDO1015I
Figure 92
DANGER!
Fire And Explosion Hazard!
Diesel fuel is flammable and explosive under certain
conditions.
When you remove any fuel system component to perform
maintenance (such as changing the fuel filter) place an
approved container under the opening to catch the fuel.
Never use a shop rag to catch the fuel. Vapors from the rag
are flammable and explosive. Wipe up any spills
immediately.
Wear eye protection. The fuel system is under pressure and
fuel could spray out when you remove any fuel system
component.
Failure to comply will result in death or serious injury.
FG009156
Figure 93
CAUTION!
Always be environmentally responsible.
Follow the guidelines of the EPA or other governmental
agencies for the proper disposal of hazardous materials
such as engine oil, diesel fuel and engine coolant. Consult
the local authorities or reclamation facility.
Never dispose of hazardous materials irresponsibly by
dumping them into a sewer, on the ground, or into ground
water or waterways.
Failure to follow these procedures may seriously harm the
environment.

23. SP001434
Page 79
Engine
That a typical fuel tank is illustrated.
1. Position an approved container under the diesel fuel tank
(1, Figure 94) to collect the contaminates.
2. Remove the fuel cap (3, Figure 94).
3. Remove the drain plug (2, Figure 94) of the fuel tank to
drain the contaminates (water, dirt, etc.) from the bottom of
the tank.
4. Drain the tank until clean diesel fuel with no water and dirt
flows out. Reinstall and tighten the drain plug firmly.
5. Reinstall the fuel cap.
6. Check for leaks.
Replace Engine Oil and Engine Oil Filter
Change the engine oil every 250 hours of operation after the
initial change at 50 hours. Replace the engine oil filter at the
same time. See “Replace Engine Oil and Engine Oil Filter” on
page -79
Figure 94
CAUTION!
Only use the engine oil specified. Other engine oils may
affect warranty coverage, cause internal engine
components to seize and / or shorten engine life.
Prevent dirt and debris from contaminating the engine oil.
Carefully clean the oil cap / dipstick and the surrounding
area before you remove the cap.
Never mix different types of engine oil. This may adversely
affect the lubricating properties of the engine oil.
Never overfill. Overfilling may result in white exhaust
smoke, engine overspeed or internal damage.
FG009156
Figure 95
CAUTION!
Always be environmentally responsible.
Follow the guidelines of the EPA or other governmental
agencies for the proper disposal of hazardous materials
such as engine oil, diesel fuel and engine coolant. Consult
the local authorities or reclamation facility.
Never dispose of hazardous materials irresponsibly by
dumping them into a sewer, on the ground, or into ground
water or waterways.
Failure to follow these procedures may seriously harm the
environment.