SERV1852-02
August 2008
TECHNICAL PRESENTATION
320D -336D HYDRAULIC EXCAVATORS -
TIER III ENGINES
INTRODUCTION
Service Training Meeting Guide
(STMG)
GLOBAL SERVICE LEARNING
320D -336D HYDRAULIC EXCAVATORS -
TIER III ENGINES
INTRODUCTION ((320D - 336D)
AUDIENCE
Level II - Service personnel who understand the principles of machine systems operation,
diagnostic equipment, and procedures for testing and adjusting.
CONTENT
This presentation provides an introduction and machine walkaround for the 320D-336D
Hydraulic Excavator. Additional presentations will cover the engines, pilot system, pumps and
controls, main control valve group, swing system, travel system, and tool control systems in
more detail. This presentation may be used for self-paced and self-directed training.
OBJECTIVES
After learning the information in this presentation, the technician will be able to:
1. identify the major components and controls of a 320D-336D Hydraulic Excavator, and
2. perform a machine walkaround inspection and daily maintenance.
REFERENCES
320D Hydraulic Excavator Specalog AEHQ5856
323D L and 323D LN Hydraulic Excavators HEHH3327
324D Hydraulic Excavator Specalog AEHQ5663
325D Hydraulic Excavator Specalog AEHQ5665
328D Hydraulic Excavator Specalog AEHQ5706
330D Hydraulic Excavator Specalog AEHQ5667

- The nomenclature for the 325D MH and 330D MH did not change.
- The nomenclature for the 325D FM and 330D FM did not change.
- The 325D HD HW did not change into 329D HD HW. This model is being discontinued.
However, the 330D HD HW changed to the 336D HD HW.
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INTRODUCTION
The Caterpillar 320D-336D range of Hydraulic Excavators incorporate design innovations and
performance improvements from the 300C Hydraulic Excavator Series and are a direct
replacement for them.
The range comprises of: 320D, 321D, 323D, 324D, 325D, 328D, & 330D, with some models
having various additional machine arrangements. During the fourth quarter of of 2008, the
329D replaced the 325D and the 336D replaced the 330D for most arrangements.
The machines feature a new cab for greater operator comfort. The cab provides the operator
with excellent visibility of processing equipment, trucks, and railcars. The cab, consoles, and
joysticks have been improved to provide a better access and understanding of all functions.
This presentation discusses the systems operation of the 320D-336D Hydraulic Excavators,
along with basic engine and machine component location.
NOTE: Most of the illustrations of the iron in this presentation will be of the 325D and
330D excavators. The other models will be configured similarly, but component
locations may be different. Some of the illustrations may show pilot iron instead of
production iron.
The most significant differences will be related to the engine compartment due to the
three different engines being used in this series of machines as well as two of the models
being compact radius (CR).
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320D-336D EXCAVATORS - TIER III ENGINES
INTRODUCTION AND SYSTEMS OPERATION

The reason for the change was to better align the machine nomenclature with the actual
machine weight. Making this change should lead to increased machine sales.
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The exceptions to this nomenclature change are as follows:
- The nomenclature for the 325D MH and 330D MH did not change.
- The nomenclature for the 325D FM and 330D FM also did not change.
- The 325D HD HW did not change into 329D HD HW. This model is being discontinued.
However, the 330D HD HW changed to the 336D HD HW.
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The 320D, 325D, and 330D can be configured as a material handler (MH). A fixed cab riser, or
as shown here, a hydraulic cab riser is available.
The cab riser provides different operating heights with excellent visibility for loading and
unloading processing equipment, trucks, and rail cars.
The 321D CR and 328D LCR are compact radius (CR) machines. With CR machines, the
machine tailswing is within the width of the undercarriage (depending on track width).
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XMachine Appearance
SIMILARITIES AND DIFFERENCES
FEATURES DIFFERENT SIMILAR SAME
XOperator s Station
XEngine
XImplement Hydraulic System
XMonitoring System
XTool Control Systems

Service and maintenance intervals have been extended to reduce machine service time and
increase machine availability.
Options include the following:
The Machine Security System (MSS): This system uses a special Caterpillar key with
an embedded electronic chip for controlling unauthorized machine operation.
Product Link: This option provides all kinds of information and working parameters
through a satellite connection between an on-board computer and the machine. Product
Link provides easier fleet management and improved preventive maintenance. PL121
and PL321 are both available.
AccuGrade: This option provides precise control of the work tool using special
software.
Auxiliary Hydraulic Options: This option allows the machine to be configured to meet
the work tool needs, while increasing its versatility.
- Single Function Circuit is suited for tools that require one-way flow with one or both
pumps, such as hammers and vibratory plate compactors.
- Double Function Circuit is suited for tools that require two-way flow, utilizing one or
two pump flows, such as thumbs, non-rotation grapples, or shears.
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For the most part the main implement hydraulic system operation for the 320D-336D is the
same as the 300C Series. The "D" Series continues using many of the "C "excavator features,
such as automatic priorities and tool control systems.
The machines use a negative flow (NFC) hydraulic system. The main control valve group and
pumps are similar to the "C" Series. Each of the models may have the components located in
different locations due to the size of the machine or the type of carbody.
The 330D/336D is equipped with a new main hydraulic pump design and is the only model
equipped with a hydraulic demand fan system.
The smaller machines can be equipped with an optional visconic demand fan if needed for
working in areas with high ambient temperatures.

The 300D excavators produced in Akashi and Aurora (for the North American Commercial
Division (NACD) can be equipped with the following factory installed tool control systems:
- System 3 (Hammer) - provides two pump flow in a single direction only. This system
also includes a mechanical line relief valve for tools requiring lower pressure settings
(single action).
- System 5 (Thumb) - provides one pump flow in both directions (extend/retract double
action) and can be controlled with a foot pedal or a joystick.
- System 14 (Multifunction) - provides one or two pump flow in one or two directions
(single action or double action). System 14 has full electronic controls. An optional,
independent medium pressure circuit is used for such applications as a rotating shear or
ditch cleaning bucket.
The System 14 functions are now controlled through the Machine ECM. A separate Tool
Control ECM as was used on the 300C Series is not needed.
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The machines produced in Akashi and Gosselies for the EAME market will have the following
factory installed optional tool control systems:
- System 16 - provides two pump flow in a single direction, has a direct return system to
the hydraulic tank, and includes a mechanical for tools requiring lower pressure settings
(single action).
- System 17 (Multifunction) - provides one or two pump flow in one or two directions
(single action or double action). System 17 has a direct return system to the hydraulic
tank, instead of the oil returning through the main control valve group. System 17 has
full electronic controls.
An independent medium pressure circuit is available with System 17 to use for
applications such as a rotating shear or a ditch cleaning bucket.
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MACHINE WALK-AROUND

the other models.
The locations and components used on the 320D, 321D, 323D, 324D and 328D will be
more similar to the 325D/329D than the 330D/336D.
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325D/329D Hydraulic Excavator
This illustration shows access to the top of the machine from the right side.
The engine access cover (1) allows access to the engine from the top of the machine.
The machine hydraulic oil tank (2) is located between the pump compartment and the diesel
fuel tank on the right side of the machine and is accessed from the top of the machine.
The diesel fuel filler cap (3) is accessed from the top of the machine.
The storage compartment (4) is located in the front of the machine.
The step and hand rail (5) at the right front of the machine can be used for access to the top of
the machine.
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The compartment behind the operator station includes the following components:
- Machine ECM (1)
- air conditioning condenser and receiver (2)
- master disconnect switch and circuit breakers (3)
- dual element, radial seal air filter (4)
- batteries (5)
- engine shutoff switch (6) (on machines with a cab riser)
The Machine ECM also includes software for the Tool Control System.

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The illustration shows the pump compartment on the right side of the machine. The
compartment is accessed from the right side of the machine when the rear access door is open.
Some of the visible components are:
- engine oil filter (1)
- pilot pump (2)
- medium pressure circuit pump (3)
- drive pump (4)
- idler pump (5)
- pilot filter (6)
- case drain filter (7)
- hydraulic system return oil filter (8)
- pressure taps for auxiliary tool solenoids (9)
- solenoids for the medium pressure circuits (10)
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