RENR8709 March 2004
FLUID POWER SYMBOLS BASIC COMPONENT SYMBOLS MAIN AUX.
Component Locations Part Machine Schematic Number Location Location
Description Accumulator - Brake
9T-6284
1
A-11
Accumulator - Pilot Pressure
149-0686
2
C-5
Accumulator - Ride Ctrl(Attach)
162-3960
3
D-13
Cooler
9Y-1834
4
C-11
Cylinder - Boom
111-8211
5
D-3
Cylinder - Bucket (Standard)
240-6029
6
C-3
Cylinder - Bucket (E-Stick)
240-6030
7
C-3
Cylinder - E-Stick
242-4278
8
B-6
Cylinder - Lift
125-7895
9
E-13, E-14
Cylinder - Stab LH
197-8079
10
C-6
Cylinder - Stab RH
197-8083
11
B-6
Cylinder - Steer
9T-1834
12
D-12
Cylinder - Stick
111-8213
13
B-3
Cylinder - Swing
169-9531
14
D-6
Cylinder - Tilt
100-7844
15
E-12
Filter
6E-5215
16
C-10
Hand Metering Unit(HMU Standard)
240-8206
17
D-11
Hand Metering Unit(HMU Emergency)
241-3757
18
D-11
Pump Gp
240-2612
19
B-10
Switch - Pressure (Ride Control)
131-9203
20
D-14
Switch - Pressure (Brake Fluid)
168-7557
21
B-13
Tank Gp
9R-2294
22
B-11
Valve - Brake
9T-7928
23
B-13
Valve - Charge
9T-3682
24
A-11
Valve - Check
9T-7114
25
E-11
Valve Gp - Cushion Swing
206-3685
26
D-6
Valve Gp - Loader (Lift,Tilt)
240-5977
27
E-11
Valve Gp - Loader (Lift,Tilt,Aux)
240-5978
28
E-11
Valve Gp - Mech (Boom,Stick,Bucket)
240-6800
29
A-3
Valve Gp - Pilot (Boom,Stick,Bucket)
236-1740
30
A-3
Valve Gp - Orifice w/bypass
214-3523
31
E-4
Valve Gp - Pattern Switching
164-2274
32
C-5
Valve Gp - Pilot LH Joystick
185-5916
33
D-5
Valve Gp - Pilot RH Joystick
185-5915
34
B-5
Valve Gp - Pilot (Stab,Swing,Mech:Aux)
239-1437
35
A-7
Valve Gp - Pilot (Stab,Swing,Mech:Aux)
239-1436
36
A-7
Valve Gp - Pilot (Stab,Mech:Swing,Aux)
240-5982
37
A-7
Valve Gp - Pilot (Stab,Mech:Swing,Aux)
240-5984
38
A-7
Valve Gp - Ride Control
190-8315
39
D-13
Valve Gp - Pilot Shut-Off
220-3392
40
C-6
Valve Gp - Stabilizer Pilot
185-5900
41
C-8
Valve Gp - Stabilizer,Pilot Oper Check
246-1604
42
C-6
PUMP or MOTOR
Ride Control Solenoid 976-OR 200-BK
LINE RESTRICTION (FIXED)
RESTRICTION
PRESSURE COMPENSATION
LINE RESTRICTION (VARIABLE)
SPRING (ADJUSTABLE)
VARIABILITY
CONTROL VALVES
SPRING
FLUID CONDITIONER
PUMP: VARIABLE and PRESSURE COMPENSATED
2-SECTION PUMP
HYDRAULIC PNEUMATIC ENERGY TRIANGLES
ATTACHMENT
LINE RESTRICTION VARIABLE and PRESSURE COMPENSATED
VALVES VALVE ENVELOPES
6
13
7
VALVE PORTS
17 18 21 TWO POSITION
ONE POSITION
TWO-WAY
THREE POSITION
CONTROL VALVES
22
CHECK VALVES
AB
AB
1 23 24
FOUR-WAY
THREE-WAY
P T SHIFTED POSITION
P T NORMAL POSITION
15
INFINITE POSITION
SPRING LOADED
BASIC SYMBOL
MEASUREMENT
ROTATING SHAFTS
39 8
20
4
PRESSURE
FLOW
TEMPERATURE
UNIDIRECTIONAL
BIDIRECTIONAL
FLUID STORAGE RESERVOIRS
Ride Control Pressure Switch F738-WH 200-BK
446D Backhoe Loader Hydraulic System
VENTED
RETURN ABOVE FLUID LEVEL
PRESSURIZED
RETURN BELOW FLUID LEVEL
COMBINATION CONTROLS
SOLENOID or MANUAL
SOLENOID
446D: DBL1-UP
SERVO
SOLENOID and PILOT or MANUAL
SOLENOID and PILOT
DETENT
THERMAL
MANUAL CONTROL SYMBOLS
MANUAL SHUTOFF
PUSH-PULL LEVER
GENERAL MANUAL
PUSH BUTTON
PEDAL
SPRING
PILOT CONTROL SYMBOLS
5
RELEASED PRESSURE
EXTERNAL RETURN
25 26 29 30
REMOTE SUPPLY PRESSURE
INTERNAL RETURN
SIMPLIFIED
CROSSING AND JOINING LINES
ACCUMULATORS
14 32
39 3 20
33 34
41 42
10 11
16 19
SPRING LOADED
9
FIXED DISPLACEMENT
3 40
LINES CROSSING
HYDRAULIC PUMPS
12
31 2
GAS CHARGED
27 28
HYDRAULIC AND PNEUMATIC CYLINDERS
SINGLE ACTING
LINES JOINING
FIXED DISPLACEMENT
VARIABLE DISPLACEMENT NON-COMPENSATED
UNIDIRECTIONAL
UNIDIRECTIONAL
BIDIRECTIONAL
BIDIRECTIONAL
DOUBLE ACTING
INTERNAL PASSAGEWAYS
HYDRAULIC MOTORS
VARIABLE DISPLACEMENT NON-COMPENSATED
INTERNAL SUPPLY PRESSURE
COMPLETE
PARALLEL FLOW
FLOW IN ONE DIRECTION
TWO POSITION
THREE POSITION
INFINITE POSITIONING
CROSS FLOW
FLOW ALLOWED IN EITHER DIRECTION
RIDE CONTROL
Machine Component Locations
Printed in U.S.A.
© 2004 Caterpillar All Rights Reserved
Accumulator (3) , Pressure Switch (20), Ride Control Valve (38)
Electrical Symbols Table Hydraulic Symbols (Electrical) 40
G Transducer (Fluid)
Electric Motor
Brake Charge Pressure Test Port
A-9
BB
Pump Discharge Pressure Test Port
B-9
CC
Signal Pressure Test Port
B-9
DD
Pilot Pressure Test Port
E-7
CC Pressure Switch (Adjustable)
Pressure Switch
Electrical Wire
Temperature Switch
Electrical Symbols (Electrical)
35 36 37 38
T
Pressure Symbol
Related Manuals Description
Media Number
Parts Manual: 446D Backhoe Loader
SEBP3972
TOP
Temperature Symbol
VIEW
Wire Number Identification Codes
Machine System: Specifications: (Hydraulic & Steering System)
RENR8707
Testing and Adjusting: (Hydraulic & Steering System)
RENR8708
Specifications: (Axles, Differentials & Brakes)
RENR8704
Testing and Adjusting: (Axles, Differentials & Brakes)
RENR8705
Electrical Schematic Example
Hydraulic Schematic Example Current Standard
Current Standard
Electrical System: Schematic: (Electrical System)
Flow Symbol
Level Symbol
Harness identification code This example indicates wire 135 in harness "AG".
RENR7781
Circuit Number Identification
DD
40
Wire
19
Wire Color
325-AG135 PK-14 325-PK
Pilot Shut Off Solenoid R912-OR 200-BK
REAR VIEW
Pilot Shut Off Valve (40)
Circuit Identification Number
Pilot Pressure Test Port (DD) Valve Group Pilot (35)(36)(37)(38) FRONT VIEW OF CAB
Brake Fluid Pressure Switch 483-BR 200-BK
Wire Color
Wire Gauge
Previous Standard
Hydraulic Pump Group (19) Brake Charge Pressure Test Port (AA) Pump Discharge Pressure Test Port (BB) Signal Pressure Tap (CC)
Wire Color
Wire
325-PK-14 B Circuit Number Identification
A
Wire Gauge (EXAMPLE VALVE)
24 Page, WDB
AA
Schematic Location
RENR8709
AA
Description
Generator
BB
Tap Locations Pressure, Sampling, and Sensor Tap Number
Transducer (Gas / Air)
M
14
13
12
10
8
9
7
6
4
5
3
2
1
X
11
F
F
X
VALVE GP 214-3523
DD
E
CYLINDER GP TILT 100-7844
E
VALVE GP LOADER LIFT/TILT 240-5977
CYLINDER GP LIFT 125-7895
PILOT PRESSURE
X
VALVE GP LOADER LIFT/TILT/AUX 240-5978
LINE PATTERNS Pressure Line
VALVE GP CHECK 9T-7114
VALVE GP LH PILOT 185-5916
Pilot / Load Sensing Pressure Drain / Return Lines
SWITCH GP PRESSURE 131-9203
Component Group VALVE GP CUSHION SWING 206-3685
CYLINDER GP STEER 9T-1834
Attachment
VALVE GP PATTERN SWITCHING 164-2274
Air Line
CALLOUTS
CYLINDER GP BOOM 111-8211
D
VALVE GP STABILIZER PILOT VALVE 185-5900
YY
Taps (Pressure, Sampling,Sensor) by letter
52
Components by number
CYLIDER GP SWING 169-9531
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS Main Pump Output. Pilot Pump Output. Load Sense Circuit. Supply Line. Drain / Return Line. Hand Metering Unit Control Circuit. Lift Cylinder Control Circuit. Brake Cylinder Control Circuit. Tilt Cylinder Control Circuit. Bucket Cylinder Control Circuit. Boom Cylinder Control Circuit. Swing Cylinder Circuit. Auxiliary Cylinder Control Circuit. Stick Cylinder Control Circuit. Stabilizer Cylinder Control Circuit. Stabilizer Cylinder Control Circuit. E-Stick Cylinder Control Circuit.
ACCUMULATOR 162-3960
VALVE GP SHUT-OFF 220-3392 VALVE GP RIDE CONTROL 190-8315
HMU STD 240-8206 HMU EMERG 240-8206
COOLER 9Y-1834
ACCUMULATOR 149-0686
FILTER GP RETURN 6E-5215
CYLINDER GP BUCKET 240-6029 STANDARD: BORE:95.3 ROD:69.9 STROKE:1011 240-6030 E-STICK: BORE:95.3 ROD:69.9 STROKE:983
C TANK GP HYDRAULIC 9R-2294
RENR8709
24 Page, Color 2, WDB
BRAKE CYLINDER
SWITCH GP PRESSURE 168-7557
D
C
CYLINDER GP STABILIZER LH 197-8079 VALVE GP STABILIZER 246-1604
BRAKE CYLINDER
CYLINDER GP STABILIZER RH 197-8083
CC SIGNAL PRESSURE
B
CYLINDER GP E-STICK 242-4278
PUMP GP 240-2612
B
CYLINDER GP STICK 111-8213
VALVE GP CHARGE 9T-3682
PUMP PRESSURE
BB
VALVE GP-PILOT 239-1437 STAB, SWING, MECH:AUX 239-1436 STAB, SWING, MECH:AUX 240-5982 STAB MECH: SWING, AUX 240-5984 STAB MECH: SWING, AUX
VALVE GP BRAKE 9T-7928
VALVE GP RH PILOT 185-5915
BRAKE CHARGE PRESSURE
AA VALVE GP 236-1740 PILOT OPERATED: BOOM, STICK, BUCKET 240-6800 MECHANICAL: BOOM, STICK, BUCKET
A
A
THIS SCHEMATIC IS FOR THE 446D BACKHOE LOADER Part #: 242-2380 Components are shown installed on a fully operable machine with the key and engine off and transmission shifter in neutral.
ACCUMULATOR 9T-6284
14
13
12
11
10
9
8
7
6
5
4
3
2
1