CAT 994h wheel loader hydraulic system Schematic Manual - PDF DOWNLOAD

UENR1278-01 May 2012

VIEW OF AREA B A

994H Wheel Loader Hydraulic System

B

DWC1-UP

B 75

22

52

33

2

53

23

A

76

40

FRONT FRAME AND AXLE - RIGHT SIDE VIEW

FRONT FRAME AND AXLE - LEFT SIDE VIEW

VIEW OF AREA A

REAR FRAME - FRONT

Volume 1 of 2: Steering and Brake Circuits

3

© 2012 Caterpillar, All Rights Reserved

45 1

8

32

36

Component Location

17

78

56 49

16

55

VIEW OF AREA A (ACCUMULATORS REMOVED)

24 67

77

51

B A 34

VIEW OF AREA B (STEERING PUMP REMOVED) REAR FRAME - BRAKE COOLING TANK AND BRAKE ACCUMULATORS

31 12

REAR AXLE

BRAKE COOLER - REAR FRAME END 68

15

BEHIND AND BELOW TANK

5

66

A

39

COMPONENTS INSIDE TANK

37

26

27

4 6

46

21

G2

G1

35 63

B

30

44

42 43

72

Accumulator GP - Brake

348-9290

1

Brake GP - Parking

116-1339

2

J-3

Breather - Hydraulic (Brake Cooling Tank)

9T-1119

3

B-4

71

Breather - Hydraulic (Steering and Brake Tank)

9T-1119

4

C-7

143-4218

5

B-13 G-12

Connector

8C-0564

6

Control GP - Foot Brake

305-5531

7

I-6

Cooler - Brake

355-1657

8

C-3

Core GP - Oil Cooler

9Y-8890

9

F-7

Cylinder GP - Steering (LH)

6E-0529

10

I-14 I-13

Cylinder GP - Steering (RH)

9T-9019

11

Filter GP - Oil

6E-0874

12

F-7

Filter GP - Oil (Hydraulic Case Drain LH)

115-2129

13

B-10

Filter GP - Oil (Hydraulic Case Drain RH)

115-2129

14

B-11

Fitting - Orifice

110-0778

15

B-13

Pump GP - Brake

102-4226

16

C-5

Pump GP - Brake Cooling

116-7341

17

B-3

Pump GP - Secondary Steering

6E-0868

18

G-9

Pump GP - Steering (LH)

263-5065

19

D-10

Pump GP - Steering (RH)

263-5064

20

C-11

Pump GP - Steering and Brake Oil Cooler

6E-0867

21

D-6

Screen - Front Left

164-3306

22

E-3

Screen - Front Right

164-3306

23

E-2

Screen - Rear Left

164-3306

24

D-3

Screen - Rear Right

164-3306

25

D-2

Screen AS - Return

7J-2656

26

B-7

Screen AS - Return

9T-9227

27

B-8

Screen GP - Steering Pump LH

251-2451

28

F-10

Screen GP - Steering Pump RH

251-2451

29

E-11

Screw - Purge (Steering Cylinder LH)

9F-2167

30

H-13

Screw - Purge (Steering Cylinder RH)

9F-2167

31

H-13

Sensor GP - Temperature (Brake Cooling Oil)

288-8390

32

B-3

Sensor GP - Temperature (Front Axle Oil)

288-8390

33

J-5

Sensor GP - Temperature (Rear Axle Oil)

288-8390

34

G-5

Sensor GP - Temperature (Steering and Brake Oil)

288-8390

35

B-9

Switch - Oil Level (Brake Cooling)

306-6875

36

B-5 B-6

Switch - Oil Level (Steering and Brake)

306-6875

37

Switch As - Limit (Park Brake)

171-7085

38

I-3

Switch AS - Pressure

255-2282

39

F-6 H-4

Switch As - Pressure (Brake)

175-3244

40

Switch As - Pressure (Park Brake Oil)

327-4608

41

J-2

Switch AS - Pressure (Oil Filter Bypass LH)

339-4361

42

B-10

Switch AS - Pressure (Oil Filter Bypass RH)

339-4361

43

B-11

Switch AS - Pressure (Secondary Steering Pump)

313-5104

44

B-13

Tank GP - Hydraulic (Brake Cooling)

248-2584

45

A-4

Tank GP - Hydraulic (Steering and Brake)

307-4606

46

B-7

Valve GP - Brake Control (Parking)

106-1774

47

I-2

Valve GP - Brake Control (Service)

247-1295

48

I-5

Valve GP - Check

122-3359

49

C-4

Valve GP - Check (Brake Accumlator)

128-6847

50

E-5/D-5

Valve GP - Check (Brake Pump)

9T-6005

51

D-5

Valve GP - Check (Front Left)

9T-3752

52

E-3

Valve GP - Check (Front Right)

9T-3752

53

E-2

Valve GP - Check (Neutralizer, Steering)

149-4617

54

F-13

Valve GP - Check (Rear Left)

9T-3752

55

C-3

Valve GP - Check (Rear Right)

9T-3752

56

C-2

Valve GP - Check (Steering Pump LH)

6E-1252

57

E-10

Valve GP - Check (Steering Pump RH)

6E-1252

58

D-11

Valve GP - Cooler Bypass

264-6867

59

F-6

Valve GP - Diverter (Secondary Steering)

163-5465

60

G-10

Valve GP - Flow Compensator (Steering Pump LH)

6E-1024

61

E-9

Valve GP - Flow Compensator (Steering Pump RH)

6E-1024

62

D-12

Valve GP - Fluid Sampling

8C-3446

63

E-6

Valve GP - Pilot (Stic Steering)

249-5615

64

C-13

Valve GP - Pressure Control (Secondary Steering)

1U-2226

65

B-12

Valve GP - Pressure Control (Steering)

1U-2226

66

B-13

Valve GP - Relief (Direct Operated)

367-5058

67

D-5

Valve GP - Relief (Pump Backup)

9J-8225

68

G-12

Valve GP - Relief (Steering Cylinder Crossover)

6E-0859

69

G-14

Valve GP - Relief (Secondary Steering)

9J-0460

70

G-10

Valve GP - Shuttle

4T-1860

71

G-13

Valve GP - Steering

154-5236

72

G-13

Valve GP - Steering Neutralizer (LH)

296-5662

73

E-14

Valve GP - Steering Neutralizer (RH)

296-5662

74

E-13

Wheel GP - Final Drive and Brake (Front Left)

137-3505

75

E-3

Wheel GP - Final Drive and Brake (Front Right)

137-3505

76

E-2

Wheel GP - Final Drive and Brake (Rear Left)

137-3505

77

D-3

Wheel GP - Final Drive and Brake (Rear Right)

137-3505

78

D-2

14

11 65

69

20

13

VIEW OF AREA B 9

57 62

61

C

BRAKE AND STEERING OIL COOLER CIRCUIT

19

64 74

18 10

54 73

60 70 COMPONENT INSIDE VALVE

REAR FRAME - FRONT

VIEW OF AREA C 29

58

28

STEERING AND BRAKE HYDRAULIC TANK AND STEERING PUMPS

E-4

Connector

Check Part Numbers in the Parts Manuals for your Specific Machine.

59

VIEW OF AREA A

Part Machine Schematic Number Location Location

Description

25

50

COMPONENT NOT SHOWN

Printed in U.S.A.

Tap Location Pressure and Sampling Tap Number

Description

Schematic Location

A

Accumulator Pressure

H-3

B

Service Brake Pressure

H-4

C

Service Brake Pressure (Front)

I-5

D

Service Brake Pressure (Rear)

G-5

G1

Steering Cylinder Pressure (Left)

H-14

G2

Steering Cylinder Pressure (Right)

H-13

G3

Left Steering Pump Discharge Pressure

E-12

G4

Right Steering Pump Discharge Pressure

F-10

G5

Brake Cooling Pump Discharge Pressure

B-3

G6

Cooler Pump Discharge Pressure

E-6

G7

Front Brake Accumulator Pressure

E-4

G8

Rear Brake Accumulator Pressure

D-5

(Dimensions: 48 inches x 35 inches)

47

36 Page,

48

UENR1278-01 VOL 1 of 2

38

41

7

14

13

12

11

10

8

9

7

6

5

4

3

2

1

(2) BRAKE GP PARKING 367-8636

C

FRONT AXLE

(Dimensions: 48 inches x 35 inches)

J

J

(41) SWITCH AS PRESSURE (PARK BRAKE OIL) 327-4608

G7

G8

C

G6

(7) CONTROL GP FOOT BRAKE 305-5531

I (10) CYLINDER GP STEERING (LH) 6E-0529

(11) CYLINDER GP STEERING (RH) 9T-9019

G3

A

VIEW OF AREA A

(31) SCREW PURGE (STEERING CYLINDER RH) 9F-2167

H

G2

G1 (69) VALVE GP RELIEF (STEERING CYLINDER CROSSOVER) 6E-0859

(38) SWITCH AS LIMIT (PARK BRAKE) 171-7085

I

A

(60) VALVE GP DIVERTER (SECONDARY STEERING) 163-5465

(70) VALVE GP RELIEF (SECONDARY STEERING) 9J-0460

(72) VALVE GP STEERING 154-5236

(47) VALVE GP BRAKE CONTROL (PARKING) 106-1774

(48) VALVE GP BRAKE CONTROL (SERVICE) 247-1295

TAPS (30) SCREW PURGE (STEERING CYLINDER LH) 9F-2167

(33) SENSOR GP TEMPERATURE (FRONT AXLE OIL) 288-8390 (40) SWITCH AS PRESSURE (BRAKE) 175-3244

G4

G5

36 Page,

UENR1278-01 VOL 1 of 2

D

H

B (18) PUMP GP SECONDARY STEERING 6E-0868

(71) VALVE GP SHUTTLE 4T-1860

BRAKE RETURN

(34) SENSOR GP TEMPERATURE (REAR AXLE OIL) 288-8390

G

G

D FRONT BRAKE SUPPLY (6) CONNECTOR 8C-0564

F

(59) VALVE GP COOLER BYPASS 264-6867

(28) SCREEN GP STEERING PUMP LH 251-2451

(68) VALVE GP RELIEF (PUMP BACKUP) 9J-8225

(54) VALVE GP CHECK (NEUTRALIZER, STEERING) 149-4617

REAR BRAKE SUPPLY

REAR AXLE

(9) CORE GP OIL COOLER 9Y-8890

F

(52) VALVE GP CHECK (FRONT LEFT) 9T-3752

G4

(73) VALVE GP STEERING NEUTRALIZER (LH) 296-5662

(29) SCREEN GP STEERING PUMP RH 251-2451

(74) VALVE GP STEERING NEUTRALIZER (RH) 296-5662

E

(62) VALVE GP FLOW COMPENSATOR (STEERING PUMP RH) 6E-1024

G3

(61) VALVE GP FLOW COMPENSATOR (STEERING PUMP LH) 6E-1024

(57) VALVE GP CHECK (STEERING PUMP LH) 6E-1252 (58) VALVE GP CHECK (STEERING PUMP RH) 6E-1252

(63) VALVE GP FLUID SAMPLING 8C-3446

G6

G7

(21) PUMP GP STEERING AND BRAKE OIL COOLER 6E-0867

(19) PUMP GP STEERING (LH) 263-5065

(66) VALVE GP PRESSURE CONTROL (STEERING) 1U-2226

(44) SWITCH AS PRESSURE (SECONDARY STEERING PUMP) 313-5104

(43) SWITCH AS PRESSURE (OIL FILTER BYPASS RH) 339-4361

(15) FITTING ORIFICE 110-0778

E (76) WHEEL GP FINAL DRIVE AND BRAKE (FRONT RIGHT) 137-3505

D

(64) VALVE GP PILOT (STIC STEERING) 249-5615

(23) SCREEN FRONT RIGHT 164-3306

(50) VALVE GP CHECK (BRAKE ACCUMULATOR) 128-6847

(51) VALVE GP CHECK (BRAKE PUMP) 9T-6005

C

(75) WHEEL GP FINAL DRIVE AND BRAKE (FRONT LEFT) 137-3505

G8

(78) WHEEL GP FINAL DRIVE AND BRAKE (REAR RIGHT) 137-3505

(25) SCREEN REAR RIGHT 164-3306

(8) COOLER BRAKE 355-1657

(4) BREATHER HYDRAULIC (STEERING AND BRAKE TANK) 9T-1119

(3) BREATHER HYDRAULIC (BRAKE COOLING TANK) 9T-1119

(77) WHEEL GP FINAL DRIVE AND BRAKE (REAR LEFT) 137-3505

(56) VALVE GP CHECK (REAR RIGHT) 9T-3752

C

(55) VALVE GP CHECK (REAR LEFT) 9T-3752

(49) VALVE GP CHECK 122-3359 (37) SWITCH OIL LEVEL (STEERING AND BRAKE) 306-6875

D

(16) PUMP GP BRAKE 102-4226 (24) SCREEN REAR LEFT 164-3306

(67) VALVE GP RELIEF (DIRECT OPERATED) 367-5058

(42) SWITCH AS PRESSURE (OIL FILTER BYPASS LH) 339-4361

(53) VALVE GP CHECK (FRONT RIGHT) 9T-3752

(39) SWITCH AS PRESSURE (1) ACCUMULATOR GP 255-2282 BRAKE 348-9290

(12) FILTER GP OIL 6E-0874

(20) PUMP GP STEERING (RH) 263-5064

(22) SCREEN FRONT LEFT 164-3306

G5 (17) PUMP GP BRAKE COOLING 116-7341

LINE PATTERNS Pressure Line Pilot / Load Sensing Pressure Drain / Return Lines Component Group

B

(36) SWITCH OIL LEVEL (BRAKE COOLING) 306-6875

PS

PS

(32) SENSOR GP TEMPERATURE (BRAKE COOLING OIL) 288-8390

HS

HS

B

CALLOUTS YY

Callout Number (Machine Location from Component LocationsTable)

Taps (Pressure, Sampling, Sensor - by letter) (52) VALVE GP - CONTROL 138-1234 Part Number

Component Name

HYDRAULIC CIRCUIT COLOR DESCRIPTIONS

(14) FILTER GP OIL (HYDRAULIC CASE DRAIN RH) 115-2129

(65) VALVE GP PRESSURE CONTROL (SECONDARY STEERING) 1U-2226

(5) CONNECTOR 143-4218

A

(13) FILTER OIL (HYDRAULIC CASE DRAIN LH) 115-2129

(35) SENSOR GP TEMPERATURE (STEERING AND BRAKE OIL) 288-8390

(27) SCREEN AS RETURN 9T-9227

(26) SCREEN AS RETURN 7J-2656

(46) TANK GP HYDRAULIC (STEERING AND BRAKE) 307-4606

STEERING PUMP OUTPUT STEERING AND BRAKE OIL COOLER PUMP OUTPUT SECONDARY PUMP OUTPUT STEERING CIRCUIT SUPPLY LINE BRAKE CIRCUIT DRAIN / RETURN LINE BRAKE PUMP OUTPUT PARK BRAKE CIRCUIT BRAKE COOLING CIRCUIT ELECTRICAL CIRCUITS

(45) TANK GP HYDRAULIC (BRAKE COOLING) 248-2584

A THIS SCHEMATIC IS FOR THE 994H WHEEL LOADER HYDRAULIC SYSTEM VOLUME 1 of 2: STEERING AND BRAKE CIRCUITS MEDIA NUMBER: UENR1278-01 SCHEMATIC PART NUMBER: 327-5451, CHANGE: 01, VERSION: - (STEERING) 248-2712, CHANGE: 03, VERSION: - (BRAKES) Components are shown installed on a fully operable machine with the key and engine off, transmission shifter in neutral and with parking brake set.

Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations.

14

13

12

11

10

9

8

7

6

5

4

3

2

1

Component Location

107 108 109 110 111 147

99 100 101 102 150 128 151 136

91 169 98 97 96 95

90 125

HYDRAULIC TANK

OIL COOLING

LIFT AND TILT CYLINDERS 123

121

158

127 122 174 124

149 160

141

168

93 182 126

166

181

86

157 184

156

88

132 163

154

C

183

188 189

F-12 G-9

Actuator GP - Pilot Control (Dump, Operator Right Valve, Right Tilt Cylinder)

217-6720

82

H-6

Actuator GP - Pilot Control (Lower, Operator Left Valve, Left Lift Cylinder)

217-6720

83

G-10

Actuator GP - Pilot Control (Lower, Operator Right Valve, Right Lift Cylinder)

217-6720

84

H-5

Actuator GP - Pilot Control (Rack, Operator Left Valve, Left Tilt Cylinder)

217-6720

85

H-9

Actuator GP - Pilot Control (Rack, Operator Right Valve, Right Tilt Cylinder)

217-6720

86

I-6

Actuator GP - Pilot Control (Raise, Operator Left Valve, Left Lift Cylinder)

217-6720

87

H-10

Actuator GP - Pilot Control (Raise, Operator Right Valve, Right Lift Cylinder)

217-6720

88

H-5

Connector AS

222-6869

89

E-12

Connector AS - Left Lift Cylinder Head End

8I-6347

90

J-10

Connector AS - Left Lift Cylinder Rod End

8I-6347

91

J-10

Connector AS - Operator Left Valve

8I-6347

92

H-9

Connector AS - Operator Right Valve

8I-6347

93

H-7

Cooler GP - Brake

179-3642

94

C-12

Cylinder GP - Lift Left (Extended High Lift)

322-1579

95

J-10

Cylinder GP - Lift Left (High Lift)

288-4468

96

J-10

Cylinder GP - Lift Left (Standard Lift)

193-4076

97

J-10

Cylinder GP - Lift Left (Super High Lift)

247-4565

98

J-10

Cylinder GP - Lift Right (Extended High Lift)

322-1579

99

J-5

Cylinder GP - Lift Right (High Lift)

288-4468

100

J-5

Cylinder GP - Lift Right (Standard Lift)

193-4076

101

J-5

Cylinder GP - Lift Right (Super High Lift)

247-4565

102

J-5

Cylinder GP - Tilt Left (Extended High Lift)

322-3142

103

J-9

Cylinder GP - Tilt Left (High Lift)

341-6034

104

J-9

Cylinder GP - Tilt Left (Standard Lift)

353-3913

105

J-9

Cylinder GP - Tilt Left (Super High Lift)

353-4654

106

J-9 J-6

Cylinder GP - Tilt Right (Extended High Lift)

322-3141

107

Cylinder GP - Tilt Right (High Lift)

341-6033

108

J-6

Cylinder GP - Tilt Right (Standard Lift)

353-3912

109

J-6

Cylinder GP - Tilt Right (Super High Lift)

353-4653

110

J-6

Filter GP - Cooler

6E-0874

111

C-12

Filter GP - Hydraulic Case Drain 1

115-2129

112

C-9

Filter GP - Hydraulic Case Drain 2

115-2129

113

C-8

Filter GP - Oil 1

341-1861

114

B-9

Filter GP - Oil 2

341-1861

115

B-7

Filter GP - Transmission Oil

353-0454

116

E-12

Fitting - Quick Disconnect (Operator Center)

6V-3965

117

C-9

Fitting - Quick Disconnect (Operator Left) 1

6V-3965

118

C-6

Fitting - Quick Disconnect (Operator Left) 2

6V-3965

190

C-6

Fitting - Quick Disconnect (Operator Right)

6V-3965

119

C-10

Gauge - Sight (Oil)

147-9560

120

A-9

Pump GP - Implement (Operator Center)

315-3144

121

E-8

Pump GP - Implement (Operator Right)

325-9799

122

E-7

Pump GP - Implement (Operator Right)

330-9389

123

E-10

Pump GP - Pilot System Hydraulic Oil Cooler

245-0963

124

D-12

Screen AS

9T-9227

125

A-10

Screen AS - Operator Center

6E-5065

126

C-8

Screen AS - Operator Right

6E-5065

127

C-10 A-11

Screen GP

7J-2656

128

Screen GP - Implement (Operator Center)

251-2451

129

E-8

Screen GP - Implement (Operator Left) 1

251-2451

130

D-6

Screen GP - Implement (Operator Left) 2

251-2451

131

C-6

Screen GP - Implement (Operator Right)

251-2451

132

E-10

Screw - Purge (Left Tilt Cylinder Head End)

9F-2167

133

I-9

Screw - Purge (Left Tilt Cylinder Rod End)

9F-2167

134

J-9

Sensor - Oil Level

306-6875

135

A-9

Sensor AS - Temperature (Hydraulic Oil)

256-6453

136

A-12

Sensor GP - Pressure (Implement Pilot)

349-1178

137

E-12

Sensor GP - Pressure (Left Lift Cylinder Head End)

349-1178

138

J-10

Sensor GP - Pressure (Left Lift Cylinder Rod End)

349-1178

139

J-10

Sensor GP - Pressure (Operator Left Valve)

344-7391

140

H-9

Sensor GP - Pressure (Operator Right Valve)

344-7391

141

H-7

Switch AS - Pressure (Filter Bypass)

349-6097

142

E-12

Switch AS - Pressure (Oil Filter Bypass) 1

339-4361

143

C-9

Switch AS - Pressure (Oil Filter Bypass) 2

339-4361

144

B-9

Switch AS - Pressure (Oil Filter Bypass) 3

339-4361

145

C-8

Switch AS - Pressure (Oil Filter Bypass) 4

339-4361

146

B-7

Switch GP - Pressure (Cooler Filter Bypass)

255-2282

147

C-12

Tank - Expansion (LH)

321-7838

148

A-8

Tank - Expansion (RH)

321-7838

149

A-9 A-11

Tank GP - Hydraulic

336-6665

150

Tube AS

322-1673

151

G-5

Valve - Operator Left Valve

6E-1291

152

G-10

Valve - Operator Left Valve 1

102-4156

153

H-9

Valve - Operator Left Valve 2

102-4156

154

I-10

Valve - Operator Right Valve

6E-1291

155

G-6

Valve - Operator Right Valve 1

102-4156

156

H-6 H-6

Valve - Operator Right Valve 2

102-4156

157

Valve GP - Breaker Relief

133-1963

158

A-6

Valve GP - Breaker Relief (LH)

220-0812

159

A-7

Valve GP - Breaker Relief (RH)

220-0812

160

A-8

Valve GP - Check

239-1132

161

G-11

Valve GP - Check

4T-5896

162

I-11

Valve GP - Check and Relief (Operator Center)

275-4098

163

D-7

Valve GP - Check and Relief (Operator Left) 1

275-4098

164

D-5

Valve GP - Check and Relief (Operator Left) 2

275-4098

165

C-5

Valve GP - Check and Relief (Operator Right)

275-4098

166

D-9

Valve GP - Control (Operator Left Valve)

326-7714

167

I-11

Valve GP - Control (Operator Right Valve)

326-7715

168

I-5

Valve GP - Cooler Bypass (Hydraulic Oil)

264-6867

169

C-12

Valve GP - Fluid Sampling

8C-3446

170

D-12

Valve GP - Makeup (Right Lift Cylinder Rod End)

160-7439

171

I-5

Valve GP - Manual Lower

112-1817

172

H-11

Valve GP - Pressure Reducing

370-0438

173

I-11

Valve GP - Relief (Hydraulic Oil Cooler Bypass)

245-4891

174

C-11

Valve GP - Relief (Left Lift Cylinder Head End)

352-2906

175

I-10

Valve GP - Relief (Left Tilt Cylinder Head End)

129-8293

176

I-9

Valve GP - Relief (Left Tilt Cylinder Rod End)

352-2907

177

I-9

Valve GP - Relief (Operator Left) 1

143-8912

178

D-6

Valve GP - Relief (Operator Left) 2

143-8912

179

C-6

Valve GP - Relief (Right Lift Cylinder Head End)

352-2906

180

I-5

Valve GP - Relief (Right Tilt Cylinder Head End)

129-8293

181

I-6

Valve GP - Relief (Right Tilt Cylinder Rod End)

352-2907

182

I-6 D-8

Valve GP - Relief (Operator Center)

143-8912

183

Valve GP - Relief (Operator Right)

143-8912

184

D-9

Valve GP - Sequence

336-4809

185

E-12

Valve GP - Shuttle

4T-1860

186

I-10

Valve GP - Solenoid

151-7455

187

G-11

Valve GP - Solenoid (Load Sensing Operator Left Valve)

173-7455

188

F-10

173-7455

189

G-6

Valve GP - Solenoid (Load Sensing Operator Right Valve) Check Part Numbers in the Parts Manuals for your Specific Machine.

84 129

80 81

994H Wheel Loader Hydraulic System DWC1-UP

Volume 2 of 2: Implement System

© 2012 Caterpillar, All Rights Reserved

FLUID POWER SYMBOLS BASIC COMPONENT SYMBOLS MAIN

PUMP OR MOTOR

FLUID CONDITIONER

SPRING

CONTROL VALVES

VARIABILITY

SPRING (ADJUSTABLE)

LINE RESTRICTION (VARIABLE)

PRESSURE COMPENSATION

ONE POSITION

TWO POSITION

P T

TWO - WAY

THREE - WAY

FOUR - WAY

SHIFTED POSITION

BASIC SYMBOL

INFINITE POSITION

SPRING LOADED

SHUTTLE

PILOT CONTROLLED

FLUID STORAGE RESERVOIRS

PRESSURIZED

VENTED

RETURN ABOVE FLUID LEVEL

RETURN BELOW FLUID LEVEL

MEASUREMENT

PRESSURE

ROTATING SHAFTS

TEMPERATURE

FLOW

UNIDIRECTIONAL

BIDIRECTIONAL

COMBINATION CONTROLS

SOLENOID

SOLENOID OR MANUAL

SOLENOID & PILOT

SOLENOID & PILOT OR MANUAL

SERVO

THERMAL

DETENT

MANUAL CONTROL SYMBOLS

GENERAL MANUAL

MANUAL SHUTOFF

PUSH BUTTON

PEDAL

PILOT CONTROL SYMBOLS

INTERNAL RETURN

SPRING

REMOTE SUPPLY PRESSURE

131

SIMPLIFIED

LINES CROSSING

SINGLE ACTING

HYDRAULIC MOTORS FIXED DISPLACEMENT

VARIABLE DISPLACEMENT NON-COMPENSATED

BIDIRECTIONAL

BIDIRECTIONAL

DOUBLE ACTING

INTERNAL PASSAGEWAYS

VARIABLE DISPLACEMENT NON-COMPENSATED

UNIDIRECTIONAL

INTERNAL SUPPLY PRESSURE

HYDRAULIC & PNEUMATIC CYLINDERS

LINES JOINING

UNIDIRECTIONAL

178

COMPLETE

CROSSING & JOINING LINES

GAS CHARGED

FIXED DISPLACEMENT

INFINITE POSITIONING

3 POSITION

FLOW IN ONE DIRECTION

PARALLEL FLOW

CROSS FLOW

2 POSITION

FLOW IN EITHER DIRECTION

HYDRAULIC OIL COOLER COMPONENTS AND LOAD SENSING VALVES

130

FRONT FRAME - REAR LEFT VIEW

161

ATTACHMENT

CHECK VALVES

HYDRAULIC PUMPS

80

LINE RESTRICTION (VARIABLE & PRESSURE COMPENSATED)

P T

NORMAL POSITION

SPRING LOADED

165

117

PUMP (VARIABLE & PRESSURE COMPENSATED)

A B

EXTERNAL RETURN

VIEW OF AREA C

190

PUMP (2 - SECTION)

180

179

187

AUX

VALVE PORTS

CONTROL VALVES AB

ACCUMULATORS

164

LINE RESTRICTION (FIXED)

HYDRAULIC PNEUMATIC ENERGY TRIANGLES

THREE POSITION

RELEASED PRESSURE

171

153

RESTRICTION

VALVES

VALVE ENVELOPES

PUSH - PULL LEVER

82

Printed in U.S.A.

G3 119

G4

G2

ELECTRICAL SYMBOLS TABLE

118

HYDRAULIC SYMBOLS (ELECTRICAL)

G1 G5

148 159 144

114

G

G9

143 112

185

M

TRANSDUCER (FLUID)

TRANSDUCER (GAS / AIR)

GENERATOR

ELECTRIC MOTOR

PRESSURE SWITCH

PRESSURE SWITCH (ADJUSTABLE)

TEMPERATURE SWITCH

ELECTRICAL WIRE

142

VIEW OF AREA A

G6

116

140 92

177

133

120

170

134

167

85 176

G7

B

137 89

G8

A

Tap Location Pressure and Sampling Tap Number

Description

Schematic Location

G1

Right Implement Pump Discharge Pressure

E-9

G2

Center Implement Pump Discharge Pressure

E-8

G3

Left Rear Implement Pump Discharge Pressure

D-6

G4

Left Front Implement Pump Discharge Pressure

D-6

G5

Implement Pilot Pressure

E-12

G6

Lift Rod End Cylinder Pressure

I-10

G7

Lift Head End Cylinder Pressure

I-10

G8

Tilt Rod End Cylinder Pressure

J-9

G9

Tilt Head End Cylinder Pressure

J-10

ELECTRICAL SYMBOLS (ELECTRICAL)

T

PRESSURE SWITCH

TEMPERATURE SWITCH

LEVEL SWITCH

FLOW SWITCH

WIRE NUMBER IDENTIFICATION CODES

ELECTRICAL SCHEMATIC EXAMPLE

HYDRAULIC SCHEMATIC EXAMPLE

CURRENT STANDARD

CURRENT STANDARD

HARNESS IDENTIFICATION CODE THIS EXAMPLE INDICATES WIRE 135 IN HARNESS “AG” WIRE

155 CIRCUIT NUMBER IDENTIFICATION

87

146

81

173

175 139

VIEW OF AREA B 162

WIRE

WIRE GAUGE

325-PK

WIRE COLOR

B

325-PK-14

113

172

CIRCUIT NUMBER IDENTIFICATION

145

186

FRONT FRAME - REAR RIGHT VIEW

WIRE COLOR

WIRE COLOR

PREVIOUS STANDARD

115

138

83

CIRCUIT NUMBER IDENTIFICATION

325-AG135 PK-14

TAP LOCATIONS

WIRE GAUGE

A

(EXAMPLE VALVE)

(Dimensions: 48 inches x 35 inches)

103 104 105 106

245-2975 217-6720

36 Page,

94

Accumulator GP - Pilot Actuator GP - Pilot Control (Dump, Operator Left Valve, Left Tilt Cylinder)

UENR1278-01 VOL 2 of 2

Description

135

UENR1278-01 May 2012

Machine Schematic Part Number Location Location

13

12

11

10

(Dimensions: 48 inches x 35 inches)

J

(91) CONNECTOR AS LEFT LIFT CYLINDER ROD END 8I-6347

AIR BLEED

(139) SENSOR GP PRESSURE (LEFT LIFT CYLINDER ROD END) 349-1178 (167) VALVE GP CONTROL (OPERATOR LEFT VALVE) 326-7714

8

9

(138) SENSOR GP PRESSURE (LEFT LIFT CYLINDER HEAD END) 349-1178 CYLINDER GP - TILT (LEFT) (90) CONNECTOR AS (105) 353-3913 (STANDARD LIFT) LEFT LIFT CYLINDER HEAD END (104) 341-6034 (HIGH LIFT) 8I-6347 (106) 353-4654 (SUPER HIGH LIFT) (103) 322-3142 (EXTENDED HIGH LIFT)

CYLINDER GP - LIFT (LEFT) (97) 193-4076 (STANDARD LIFT) (96) 288-4468 (HIGH LIFT) (98) 247-4565 (SUPER HIGH LIFT) (95) 322-1579 (EXTENDED HIGH LIFT)

G9

7

5

CYLINDER GP - TILT (RIGHT) (109) 353-3912 (STANDARD LIFT) (108) 341-6033 (HIGH LIFT) (110) 353-4653 (SUPER HIGH LIFT) (107) 322-3141 (EXTENDED HIGH LIFT)

(133) SCREW PURGE (LEFT TILT CYLINDER HEAD END) 9F-2167

4

3

2

1

CYLINDER GP - LIFT (RIGHT) (101) 193-4076 (STANDARD LIFT) (100) 288-4468 (HIGH LIFT) (102) 247-4565 (SUPER HIGH LIFT) (99) 322-1579 (EXTENDED HIGH LIFT)

AIR BLEED

(134) SCREW PURGE (LEFT TILT CYLINDER ROD END) 9F-2167

G8

6

(181) VALVE GP RELIEF (RIGHT TILT CYLINDER HEAD END) 129-8293

J

(168) VALVE GP CONTROL (OPERATOR RIGHT VALVE) 326-7715

G6

(180) VALVE GP RELIEF (RIGHT LIFT CYLINDER HEAD END) 352-2906

(177) VALVE GP RELIEF (LEFT TILT CYLINDER ROD END) 352-2907

I (173) VALVE GP PRESSURE REDUCING 370-0438

(86) ACTUATOR GP PILOT CONTROL (RACK, OPERATOR RIGHT VALVE, RIGHT TILT CYLINDER) 217-6720

(175) VALVE GP RELIEF (LEFT LIFT CYLINDER HEAD END) 352-2906

(162) VALVE GP CHECK (87) ACTUATOR GP 4T-5896 PILOT CONTROL (RAISE, OPERATOR LEFT VALVE, LEFT LIFT CYLINDER) 217-6720

(85) ACTUATOR GP PILOT CONTROL (RACK, OPERATOR LEFT VALVE, LEFT TILT CYLINDER) 217-6720

RACK

RAISE

(172) VALVE GP MANUAL LOWER 112-1817

(171) VALVE GP MAKEUP (RIGHT LIFT CYLINDER ROD END) 160-7439

(182) VALVE GP RELIEF (RIGHT TILT CYLINDER ROD END) 352-2907

(176) VALVE GP RELIEF (LEFT TILT CYLINDER HEAD END) 129-8293

G7

(186) VALVE GP SHUTTLE 4T-1860

36 Page,

UENR1278-01 VOL 2 of 2

14

RACK

I

(88) ACTUATOR GP PILOT CONTROL (RAISE, OPERATOR RIGHT VALVE, RIGHT LIFT CYLINDER) 217-6720

RAISE

(156) VALVE OPERATOR RIGHT VALVE 1 102-4156 (141) SENSOR GP PRESSURE (OPERATOR RIGHT VALVE) 344-7391

(153) VALVE OPERATOR LEFT VALVE 1 102-4156

H

H (140) SENSOR GP PRESSURE (OPERATOR LEFT VALVE) 344-7391 HYDRAC

(187) VALVE GP SOLENOID 151-7455

ON/OFF

(82) ACTUATOR GP PILOT CONTROL (DUMP, OPERATOR RIGHT VALVE, RIGHT TILT CYLINDER) 217-6720

(92) CONNECTOR AS OPERATOR LEFT VALVE 8I-6347

(161) VALVE GP CHECK 239-1132

G

(93) CONNECTOR AS OPERATOR RIGHT VALVE 8I-6347

DUMP

LOWER

(83) ACTUATOR GP PILOT CONTROL (LOWER, OPERATOR LEFT VALVE, LEFT LIFT CYLINDER) 217-6720

(81) ACTUATOR GP PILOT CONTROL (DUMP, OPERATOR LEFT VALVE, LEFT TILT CYLINDER) 217-6720

(84) ACTUATOR GP PILOT CONTROL (LOWER, OPERATOR RIGHT VALVE, RIGHT LIFT CYLINDER) 217-6720

LOWER

DUMP

(155) VALVE OPERATOR RIGHT VALVE 6E-1291

(157) VALVE OPERATOR RIGHT VALVE 2 102-4156

(154) VALVE OPERATOR LEFT VALVE 2 102-4156

G

(151) TUBE AS 322-1673

(152) VALVE OPERATOR LEFT VALVE 6E-1291

(189) VALVE GP SOLENOID (LOAD SENSING OPERATOR RIGHT VALVE) 173-7455

F

F (80) ACCUMULATOR GP PILOT 245-2975

(188) VALVE GP SOLENOID (LOAD SENSING OPERATOR LEFT VALVE) 173-7455

(137) SENSOR GP PRESSURE (IMPLEMENT PILOT) 349-1178

(89) CONNECTOR AS 8I-6347

(185) VALVE GP SEQUENCE 336-4809

(122) PUMP GP IMPLEMENT (OPERATOR RIGHT) 330-9389

CW

G5

CCW

(132) SCREEN GP IMPLEMENT (OPERATOR RIGHT) 251-2451

P

P1

E

(121) PUMP GP IMPLEMENT (OPERATOR CENTER) 315-3144

(123) PUMP GP IMPLEMENT (OPERATOR LEFT) 325-9799

CW

(129) SCREEN GP IMPLEMENT (OPERATOR CENTER) 251-2451

L2

L1

E

D

G2

G1

(142) SWITCH AS PRESSURE (FILTER BYPASS) 349-6097

(116) FILTER GP TRANSMISSION OIL 353-0454

T2 R

Q M A X

P1

M1g

M1g

(124) PUMP GP PILOT SYSTEM HYDRAULIC OIL COOLER 245-0963

AIR BLEED

S1

ACTR Q MIN

D1

(184) VALVE GP RELIEF (OPERATOR RIGHT) 143-8912 (166) VALVE GP CHECK AND RELIEF (OPERATOR RIGHT) 275-4098

Q MAX M2g

(111) FILTER GP COOLER 6E-0874

S1

ACTR Q MIN

D1

Q MAX

(183) VALVE GP RELIEF (OPERATOR CENTER) 143-8912

SA2

(94) COOLER GP BRAKE 186-0058

AIR BLEED (174) VALVE GP RELIEF (HYDRAULIC OIL COOLER BYPASS) 245-4891

(169) VALVE GP COOLER BYPASS (HYDRAULIC OIL) 264-6867

SA1

24 VDC

(163) VALVE GP CHECK AND RELIEF (OPERATOR CENTER) 275-4098

SA2

AIR BLEED

SA1

(165) VALVE GP CHECK AND RELIEF (OPERATOR LEFT) 2 275-4098

R T2 T1

G4

Q MIN (179) VALVE GP RELIEF (OPERATOR LEFT) 2 143-8912

24 VDC (126) SCREEN AS OPERATOR CENTER 6E-5065

AIR BLEED

AIR BLEED

C

(145) SWITCH AS PRESSURE (OIL FILTER BYPASS) 3 339-4361

(113) FILTER GP HYDRAULIC CASE DRAIN 2 115-2129 (118) FITTING QUICK DISCONNECT (OPERATOR LEFT) 1 6V-3965

(146) SWITCH AS PRESSURE (OIL FILTER BYPASS) 4 339-4361

(112) FILTER GP HYDRAULIC CASE DRAIN 1 115-2129

D

G2 Q M A X

EHV (127) SCREEN AS OPERATOR RIGHT 6E-5065

(178) VALVE GP RELIEF (OPERATOR LEFT) 1 143-8912

Mb B

M1

(119) FITTING QUICK DISCONNECT (OPERATOR RIGHT) 6V-3965 (143) SWITCH AS PRESSURE (OIL FILTER BYPASS) 1 339-4361

S

M2g

EHV

(164) VALVE GP CHECK AND RELIEF (OPERATOR LEFT) 1 275-4098

G3

Ma

(117) FITTING QUICK DISCONNECT (OPERATOR CENTER) 6V-3965

(147) SWITCH GP PRESSURE (COOLER FILTER BYPASS) 255-2282

(130) SCREEN GP IMPLEMENT (OPERATOR LEFT) 1 251-2451

G1 A

AIR BLEED

(170) VALVE FLUID SAMPLING 8C-3446

C

T1

M1 P1

D

Q MIN

(131) SCREEN GP IMPLEMENT (OPERATOR LEFT) 2 251-2451

(115) FILTER GP OIL 2 341-1861

(114) FILTER GP OIL 1 341-1861

LINE PATTERNS

(144) SWITCH AS PRESSURE (OIL FILTER BYPASS) 2 339-4361

B

Pressure Line Pilot / Load Sensing Pressure Drain / Return Lines

B

Component Group

CALLOUTS YY

Callout Number (Machine Location from Component LocationsTable)

(128) SCREEN GP 7J-2656

(135) SENSOR OIL LEVEL 306-6875

(136) SENSOR AS TEMPERATURE (HYDRAULIC OIL) 256-6453

A

(120) GAUGE SIGHT (OIL) 147-9560

(125) SCREEN AS 9T-9227

(149) TANK GP EXPANSION (RH) 321-7838

(160) VALVE GP BREAKER RELIEF (RH) 220-0812

(148) TANK GP EXPANSION (LH) 321-7838

(52) VALVE GP - CONTROL 138-1234 Part Number

Component Name

HYDRAULIC CIRCUIT COLOR DESCRIPTIONS

(158) VALVE GP BREAKER RELIEF 133-1963

(150) TANK GP HYDRAULIC 336-6665

Taps (Pressure, Sampling, Sensor - by letter)

PILOT PUMP OUTPUT OPERATOR LEFT PUMP OUTPUT CENTER PUMP OUTPUT SUPPLY LINE LIFT CYLINDER CIRCUIT DRAIN / RETURN LINE OPERATOR RIGHT PUMP OUTPUT TILT CYLINDER CIRCUIT BRAKE COOLING

(159) VALVE GP BREAKER RELIEF (LH) 220-0812

THIS SCHEMATIC IS FOR THE 994H WHEEL LOADER HYDRAULIC SYSTEM VOLUME 2 of 2: IMPLEMENT SYSTEM MEDIA NUMBER: UENR1278-01 SCHEMATIC PART NUMBER: 327-5422, CHANGE: 02, VERSION: Components are shown installed on a fully operable machine with the key and engine off, transmission shifter in neutral and with parking brake set.

Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations.

14

13

12

11

10

9

8

7

6

5

4

3

2

1

A