CAT 320D, 323D Schematics

INTERACTIVE SCHEMATIC

ELECTRICAL SYMBOLS

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Component

Connector

Schematic

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Chassis View

Cab View

Engine View

X

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EC-C2

EC-C3

E-C60

E-C61

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EC-C1

Click on any text that is BLUE and

underlined. These are hyperlinks

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schematic and machine views.

HOTKEYS (Keyboard Shortcuts)

FUNCTION

Zoom In

Zoom Out

Fit to Page

Hand Tool

Find

“CTRL” / “+”

“CTRL” / “-”

“CTRL” / “0” (zero)

“SPACEBAR” (hold down)

“CTRL” / “F”

KEYS

VIEW ALL CALLOUTS

When only one callout is showing on a
machine view, clicking on this button will
make all of the callouts visible. This
button is located in the top right corner
of every machine view page.

BASIC HYDRAULIC

COMPONENT SYMBOLS

Pressure

Switch

T

Temperature

Switch

Level

Switch

Flow

Switch

Circuit Breaker

Click here to view the

Schematic Symbols

and Definitions page

Pump

or Motor

Fluid

Conditioner

(Adjustable)

Variability

Spring

SCHEMATIC SYMBOLS AND DEFINITIONS

One Position

Two-way

A B

P T

Normal Position

Basic

Symbol

VALVES

ENVELOPES

Two Position

PORTS

Three-Way

CONTROL

A B

P T

Shifted Position

CHECK

Spring

Loaded

Shuttle

Three Position

Four-Way

Infinite Position

Pilot

Controlled

PILOT CONTROL

RELEASED PRESSURE

INTERNAL PASSAGEWAYS

FLOW IN ONE

DIRECTION

Infinite

Positioning

FLOW ALLOWED IN
EITHER DIRECTION

Two

Position

CYLINDERS

Single Acting

Double Acting

ACCUMULATORS

Spring Loaded

Gas Charged

PARALLEL

FLOW

Three

Position

CROSS

FLOW

PUMPS

FIXED DISPLACEMENT

Unidirectional

Bidirectional

VARIABLE DISPLACEMENT

NON- COMPENSATED

Unidirectional

Bidirectional

MOTORS

FIXED DISPLACEMENT

Unidirectional

Bidirectional

VARIABLE DISPLACEMENT

NON- COMPENSATED

Unidirectional

Bidirectional

ROTATING SHAFTS

BASIC HYDRAULIC

COMPONENT SYMBOLS

Pump

or Motor

Fluid

Conditioner

Spring

Control

Valves

Restriction

Line Restriction

Variable and Pressure

Compensated

Variability

Spring

(Adjustable)

Pressure

Compensation

Line Restriction

(Variable)

Line Restriction

(Fixed)

AUX.

MAIN

2-Section

Pump

External Return

Simplified

Solenoid

Solenoid

or Manual

Solenoid
and Pilot

Push-pull Lever PedalGeneral Manual Push Button SpringManual Shutoff

Internal Return

REMOTE SUPPLY PRESSURE

Complete

Internal

Supply Pressure

COMBINATION CONTROLS

Solenoid and

Pilot or Manual

Servo

MANUAL CONTROL

Thermal

Detent

Unidirectional

Bidirectional

Attachment

Pump: Variable and

Pressure Compensated

Hydraulic Pneumatic

Energy Triangles

MEASUREMENT

Pressure

Temperature

Flow

Crossing

LINES

Joining

FLUID STORAGE RESERVOIRS

Vented Pressurized Return Above Fluid Level Return Below Fluid Level

Transducer

(Fluid)

T

HYDRAULIC SYMBOLS - ELECTRICAL

Transducer

(Gas / Air)

G

Generator

M

Electric

Motor

Pressure

Switch

Pressure Switch

(Adjustable)

Temperature

Switch

Electrical

Wire

BASIC ELECTRICAL COMPONENT SYMBOLS

Fuse: A component in an electrical circuit that will open the circuit if too much current flows through it.

Switch (Normally Open): A switch that will close at a specified point (temp, press, etc.). The circle indicates

Switch (Normally Closed): A switch that will open at a specified point (temp, press, etc.).

Ground (Wired): This indicates that the component is connected to a grounded wire.

The grounded wire is fastened to the machine.

Ground (Case): This indicates that the component does not have a wire connected to ground.

It is grounded by being fastened to the machine.

Reed Switch: A switch whose contacts are controlled by a magnet. A magnet closes the contacts of

a normally open reed switch; it opens the contacts of a normally closed reed switch.

Sender:

A component that is used with a temperature or pressure gauge.
The sender measures the temperature or pressure.
Its resistance changes to give an indication to the gauge of the temperature or pressure.

Relay (Magnetic Switch): A relay is an electrical component that is activated by electricity.

Solenoid: A solenoid is an electrical component that is activated by electricity.

It has a coil that makes an electromagnet when current flows through it.
The electromagnet can open or close a valve or move a piece of metal that can do work.

Magnetic Latch Solenoid: An electrical component that is activated by electricity and held latched by a

that the component has screw terminals and a wire can be disconnected from it.

No circle indicates that the wire cannot be disconnected from the component.

It has a coil that makes an electromagnet when current flows through it.
The electromagnet can open or close the switch part of the relay.

permanent magnet. It has two coils (latch and unlatch) that make electromagnet
when current flows through them. It also has an internal switch that places
the latch coil circuit open at the time the coil latches.

ELECTRICAL SYMBOLS

Pressure

Switch

T

Temperature

Switch

Switch

HARNESS AND WIRE SYMBOLS

Wire, Cable, or Harness Assembly Identification:

Includes Harness Identification Letters and Harness
Connector Serialization Codes (see sample).

AG-C4

Part Number: for
Connector Plug

Harness Identification Letter(s): (A, B, C, AA, AB, AC, ...)

Harness Connector Serialization Code: The "C" stands for

"Connector" and the number indicates which connector in the
harness (C1, C2, C3, ...)

L-C12
3E-5179

Fuse (5 Amps)

Harness identification code:

This example indicates wire group 325,

wire 135 in harness "AG".

1
2

1
2

111-7898

Plug

5A

Deutsch connector: Typical representation
of a Deutsch connector. The plug contains all
sockets and the receptacle contains all pins.

Sure-Seal connector: Typical representation
of a Sure-Seal connector. The plug and receptacle
contain both pins and sockets.

Level

Flow

Switch

L-C12
3E-5179

1

2

9X-1123

325-AG135 PK-14

Circuit Breaker

Receptacle
Pin or Socket Number

Component
Part Number

Wire Gauge
Wire Color

RENR7157-07

October 2012

320D and 323D Excavator
Hydraulic System - Attachment

320D:
MDE1-UP

A6F1-UP
A8F1-UP
A9F1-UP
KGF1-UP
TDH1-UP
DHK1-UP
FAL1-UP
KLM1-UP
CXY1-UP
JGZ1-UP

323D:
PBE1-UP
LFL1-UP

System 3 Prime

Printed in U.S.A.© 2012 Caterpillar, All Rights Reserved