SENR6118-01
16 Page
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 PEDALGENERAL 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
AB
PT
AB
PT
SHIFTED POSITION
INFINITE POSITION
CONTROL VALVES
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
SENR6118-01
April 1996
350 and 350 L Excavators
Hydraulic System
350:
7RK1-324
2ZL1-170
8HK1-UP
350 L:
9DK1-212
9FL1-419
3ML1-684
©
1996 Caterpillar
All Rights Reserved
Printed in U.S.A.
58
50
49
48
56
46
45
59
43
44
20
51
57
21
47
55
54
53
52
R2
IMP2
PTA
TR
BM1
BL1
BR1
AL4
dR1
HL1
SV2
SV1
AR3
AL3
AL2
R1
AL1
AR1
BL4
LS2
PP
LS1
BR3
BL3
BL2
BM2
BSIN
HL2
Ds
bL2
bL3
bR3
bL4
aR1
aL1
PF
PR
R1
R2
bL1
bR1
dR2
aR3
aL3
aL2
aL4
PG
Pi3
Pi2
Pi1
A
Pi4
DR1
DR2
DR3
TOUT
PIN
DR5
DR4
30 19
18
17 16 29 41 25 42 22 24 23 8
7
6
43
31
38
14
26
2
11
39
32
28
36 40 1019371334125153427
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
Right travel motor
Left travel motor
Swing parking brake control valve
Right swing motor
Left swing motor
Bucket cylinder
Stick cylinder
Boom cylinders
Boom drift reduction valve
Travel brake valve (right)
Travel brake valve (left)
Swivel
Swing pressure switch
Swing power control pressure switch
Stick drift reduction valve
Main control valve
Travel pressure switch
Implement pressure switch
Relief valve (travel signal)
Signal relief valve
Pilot control valve (travel left)
Pilot control valve (travel right)
Swing control valve
Pilot control valve (boom/bucket)
Pilot control valve (swing/stick)
Automatic travel speed change valve
Proportional reducing valve
Pilot filter
Bypass check valve
Back pressure valve
Swing pump
Differential relief valve
Travel speed solenoid valve
Pilot oil manifold
Pilot relief valve
Drain filter
Hydraulic tank
Pilot pump
Front pump
Rear pump
Hydraulic activation control valve
Attachment control valve
Main relief valve (right body)
Stick spool
Signal duplication valve (right body)
Selector valve
Boom control valve
Left travel control valve
Relief valve (travel signal)
Main relief valve (left body)
Compensator valve
Relief valve (bucket cylinder rod end)
Accumulator
Relief valve (bucket cylinder head end)
Relief valve (stick cylinder head end)
Combiner valve
Relief valve (boom cylinder rod end)
Neutral bypass solenoid valve
Bucket control valve
Item
No.
Item
No.
Description
COMPONENT TABLE
Description
SENR6118-01
16 Page
THIS SCHEMATIC IS FOR THE 350 AND 350L
Components are shown installed on a fully operable machine with the key and engine off.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations
aL2
aL3
IMP1
BM 2
BSIN
aR 3
bL2
R1
BL 2 AL 2
bL3
BL 3
AL 3
bR 3
BR3
AR3
LS1
dR 1
SV 2
SV 1
PP
HL 1
DS
BM1
bR1
HL 2
PR
PF
LS 2
AL4
BL4
bL4
BR1 AR1
aR 1
BL 1 AL 1
aL 1
R2
TR
bL1
PTA
PSW
IMP2
Pi 4
A
TOUT
PG
PIN
DR5
DR4
DR3
DR1
DR2
Pi1
Pi 2 Pi 3
SD1
DOWN
UP
1
2
3
4
5
15
12
14
13
11
8
7
6
9
10
16
44
52
43
53
59
54
45
46
56
21
57
48
49 50
17
18
51
20
58
19
47
55
22
23
24
25
41
42
26
33
27
34
35
28
36
37
29 30
31
38
39
32
40
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
Right travel motor
Left travel motor
Swing parking brake control valve
Right swing motor
Left swing motor
Bucket cylinder
Stick cylinder
Boom cylinders
Boom drift reduction valve
Travel brake valve (right)
Travel brake valve (left)
Swivel
Swing pressure switch
Swing power control pressure switch
Stick drift reduction valve
Main control valve
Travel pressure switch
Implement pressure switch
Relief valve (travel signal)
Signal relief valve
Pilot control valve (travel left)
Pilot control valve (travel right)
Swing control valve
Pilot control valve (boom/bucket)
Pilot control valve (swing/stick)
Automatic travel speed change valve
Proportional reducing valve
Pilot filter
Bypass check valve
Back pressure valve
Swing pump
Differential relief valve
Travel speed solenoid valve
Pilot oil manifold
Pilot relief valve
Drain filter
Hydraulic tank
Pilot pump
Front pump
Rear pump
Hydraulic activation control valve
Attachment control valve
Main relief valve (right body)
Stick spool
Signal duplication valve (right body)
Selector valve
Boom control valve
Left travel control valve
Relief valve (travel signal)
Main relief valve (left body)
Compensator valve
Relief valve (bucket cylinder rod end)
Accumulator
Relief valve (bucket cylinder head end)
Relief valve (stick cylinder head end)
Combiner valve
Relief valve (boom cylinder rod end)
Neutral bypass solenoid valve
Bucket control valve
Item
No.
Item
No.
Description
30 19
18
17 16 29 41 25 42 22 24 23 8
7
6
43
31
38
14
26
2
11
39
32
28
36 40 1019371334125153427
COMPONENT TABLE
Description
