438 HYDRAULIC SYSTEM SCHEMATIC NO.
SENR3921 April 1988
A) Continued on other side
B) Continued on other side
438 Backhoe Loader Hydraulic System
COMPONENT
NO.
COMPONENT
1
STEERING CYLINDER
26
SWING CYLINDER RELIEF VALVE
2
ATTACHMENT CROSSOVER RELIEF VAVLE
27
L.H. STABILIZER CYLINDER
3
HAND METERING UNIT
28
ATTACHMENT EXTENDABLE STICK CYLINDER
4
HMU INLET CHECK VALVE
29
BACKHOE CONTROL VALVE
5
LIFT CYLINDERS
30
RETURN RESTRICTION VALVE
6
TILT CYLINDER
31
ATTACHMENT EXT. STICK CONTROL VALVE
7
ATTACHMENT CLAM CYLINDERS
32
L.H. STABILIZER CONTROL VALVE
8
SIDESHIFT LOCK CYLINDER
33
STICK CONTROL VALVE
9
LOADER CONTROL VALVE
34
BUCKET CONTROL VALVE
11
STEERING PRIORITY VALVE
35
SWING CONTROL VALVE
12
ATTACHMENT CLAM CONTROL VALVE
36
BOOM CONTROL VALVE
13
TILT CONTROL VALVE
37
R.H. STABILIZER CONTROL VALVE
14
LIFT CONTROL VALVE
38
ATTACHMENT CONTROL VALVE
15
PUMP
41
LINE RELIEF VALVE (13 000 kPa)
16
SIDESHIFT LOCK VALVE
42
LINE RELIEF VALVE (31 000 kPa)
17
HYDRAULIC TANK AND OIL FILTERS
43
LINE RELIEF VALVE (22 000 kPa)
18
OIL COOLER BYPASS VALVE
44
LINE RELIEF VALVE (24 200 kPa)
19
OIL COOLER
45
LINE RELIEF VALVE (20 000 kPa)
20
R.H. STABILIZER CYLINDER
46
MAKEUP VALVE
21
BOOM CYLINDERS
47
ORIFICE CHECK VALVE
22
L.H. SWING CYLINDER
48
STABILIZER LOCK VALVE
23
R.H. SWING CYLINDER
49
ATTACHMENT CHECK VALVE
24
BUCKET CYLINDER
50
ATTACHMENT CHECK VALVE
25
STICK CYLINDER
52
ORIFICE CONNECTER (TWO)
3DJ1-UP TEST POINT
C) Continued on other side
PRESSURE TAP
A
PUMP PRESSURE
B
SIGNAL PRESSURE
D) Continued on other side E) Continued on other side
© 1988 Caterpillar All Rights Reserved
SENR3921 8 Page, UHE
Printed in U.S.A.