Material Caterpillar 320b 330b Hydraulic Excavators Pilot System Components Diagrams Schematics

Service Training MALAGA

320B/330B Hydraulic Excavators III. PILOT SYSTEM

The pilot system is very similar to the pilot system on the 300A with regard to components and operation.

Francis June 97

Page:

PILOT & LOGIC CONTROL SCHEMATIC

2

Pressure Switch (Implement/ AEC) Pressure Switch (Travel / AEC)

Straight Travel Valve

Boom 1

Bucket

Pilot Pump

320B - 330B HYDRAULIC EXCAVATORS

Pilot Control Valve (Joystick)

CHAPTER : Pilot System

Pilot Oil Manifold

Attachment

Right Travel

Left Travel

Swing

Stick 1

Pilot Relief Valve

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

PILOT LOGIC CIRCUIT

Stk 2

Bm 1

Bkt

Rt Trav

Return Passage

Top Pump Inlet

Nfc Parallel Passages

Page:

3

Str Trav

Atch

Bottom Pump Inlet

Lft Trav

Sw

Stk 1

Bm 2

Parallel Passages

Nfc Return Passage

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PILOT OIL MANIFOLD SCHEMATIC

4 To Logic Circuit

Return Oil

To Pump Regulator

To Stick Control Valve 2 From Stick Pilot Control Valve

LEVEL FINISH SOLENOID

121-1490

To Swing Brake TRAVEL SPEED SOLENOID

TRENCHING SOLENOID

PRESSURE REDUCING VALVE

121-1491

121-1490

111-9916

From Main Control Valve Group Pilot Pump

320B - 330B HYDRAULIC EXCAVATORS

Pilot Relieve valve

CHAPTER : Pilot System

To Hydr. Actuation Valve

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

PILOT OIL MANIFOLD (Partial)

To swing brake To Logic Circuit Hyd. Activ. Control Valve

Accumulator

Pilot Relief Valve

Check Valve Pilot Pump

Page:

5

Page: 6

RIGHT TRAVEL CONTROL VALVE

Pressure swich (Implement / AEC) Orifice

320B - 330B HYDRAULIC EXCAVATORS

Pilot line

CHAPTER : Pilot System

Pressure switch (Travel / AEC)

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

PROPORTIONAL REDUCING VALVE

SOLENOID

To Pump Suction Line

SIGNAL CURRANT INCREASE To Pump Regulator

a

(PS signal)

b Pilot Oil pump

To Pump Suction Line To Pump Regulator

SIGNAL CURRANT DECREASE

(PS signal)

Pilot Oil pump

Page:

7

a. Return Passage b. Inlet Passage

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

PILOT CONTROL VALVE

300B 123-2147

From Main Control Valve 1 3

2

c

b

a

To Main Control Valve Pilot Pump

Pilot Pump To Main Control Valve

Pilot Pressure

4000 kPa

3000 kPa

800 kPa

300B Lever Stroke

Page:

8

1. 2. 3. a. b. c.

Rod Spring Spool Line to control valve Line from control valve Return passage

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

SHOCK REDUCING VALVE (Check Valve Open)

Pilot Control Valve

Boom - 1

Shock Reducing Valve

E

Check Valve

a a. Passage

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9

Pump Assembly

320B - 330B HYDRAULIC EXCAVATORS CHAPTER : Pilot System

SHOCK REDUCING VALVE (Check Valve Closed)

Pilot Control Valve

Boom - 1

c Shock Reducing Valve

E

d b

b. Outlet Port c. Passage d. Orifice

Page:

10

Pump Assembly