©
2005 Caterpillar
All Rights Reserved
Printed in U.S.A.
RENR7029
April 2005
385C Excavators
Medium Pressure Circuit
Hydraulic System (Attachment)
ONE POSITION
TWO POSITION
THREE POSITION
VENTED
PRESSURIZED
RETURN ABOVE FLUID LEVEL
RETURN BELOW FLUID LEVEL
LINES CROSSING
LINES JOINING
TWO-WAY
THREE-WAY
FOUR-WAY
SPRING
CONTROL VALVES
RESTRICTION
LINE RESTRICTION
(FIXED)
2-SECTION PUMP
MAIN
AUX.
SPRING
(ADJUSTABLE)
VARIABILITY
LINE RESTRICTION
(VARIABLE)
LINE RESTRICTION
(VARIABLE and PRESSURE COMPENSATED)
PRESSURE
COMPENSATION
PUMP: VARIABLE and
PRESSURE COMPENSATED
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
MEASUREMENT
PRESSURE
TEMPERATURE
FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH-PULL LEVER
PEDAL
GENERAL MANUAL
PUSH BUTTON
SPRING
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
HYDRAULIC PUMPS
FLUID STORAGE RESERVOIRS
CROSSING AND JOINING LINES
VALVE ENVELOPES
VALVE PORTS
BASIC COMPONENT SYMBOLS
FLUID CONDITIONER
PUMP or MOTOR
FLUID POWER SYMBOLS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVES
PILOT CONTROL SYMBOLS
RELEASED PRESSURE
EXTERNAL RETURN
INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED
COMPLETE
INTERNAL
SUPPLY PRESSURE
ACCUMULATORS
SPRING LOADED
GAS CHARGED
SOLENOID
or MANUAL
SOLENOID
and PILOT
SOLENOID and
PILOT or MANUAL
COMBINATION CONTROLS
SOLENOID
SERVO
THERMAL
DETENT
HYDRAULIC AND PNEUMATIC CYLINDERS
DOUBLE ACTING
SINGLE ACTING
BASIC SYMBOL
SPRING LOADED
CHECK VALVES
TWO
POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW ALLOWED IN
EITHER DIRECTION
THREE
POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
A B
P T
A B
P T
SHIFTED POSITION
INFINITE POSITION
CONTROL VALVES
EDA1-UP
KGB1-UP
KBC1-UP
SBE1-UP
T2E1-UP
KKK1-UP
JCM1-UP
MNZ1-UP
WAW1-UP
Schematic
4
5
6
7
8
9
1
2
3
3
(37MPa)
(4.1MPa)
(37MPa)
(3.3MPa)
(34MPa)
(34MPa)(34MPa)
R
M
LEFT
PR
PG
E
F
SWING
D
LEFT
D
F
E
TRACK
aL4
bR1
bL1
R2
TRAVEL
(L)
TRAVEL
(R)
P
T
M2
M1
RIGHT
B
A
M
PD
L2
L1
Qmax Qmin
FWD
M1
T2T1
R
S
A
M
G
aL1
BL1
AL1
LS2
(34MPa)
FWD
aR1
bL4
D1
D2
AL4
BR1
AR1
BL4
PF
PS1
STICK
LS1
SA1
P2
P1
P1
P2
Dr
B1
SA2
IN
B
A
LS
LS
pA
pB
210
LS
210
M
REVREVOUT
RIGHT
BA
P
P1
P2
Dr
(3.3MPa)
(32MPa)
A2
aR3
aL3
bR3
bL3
(35MPa)
TT
ATT
AR3
BR3
AL3
BL3
A1
P
bL2
PR
aL2
R1
BUCKET
DOWN
BOOM
P
T
OPEN
UP
CLOSE
)(
)(
PR
A
Dr
B
Dr
Pi
Pi
Pa
Pb
Pa
Dr
Pb
Pi
Pi
B
Dr
A
PR
A
BB
A
B
L1
L
S
PSg
a2
a1
P
P
PSA3
PSA2
PSA1
PG
PIN
TOUT
DR1
DR2
DR3
Pi5
PAC
Pi3
Pi2
Pi1
Pi4
Pi6
PSA4
DR6
DR5
DR4
This Attachment Schematic is intended to
be used in conjunction with the Standard
Hydraulic Schematic in this Service Manual.
Hydraulic Schematic
255-5149
PILOT LINE
DRAIN LINE
MAIN CONNECTOR LINE
