TM 5-3805-281-24-1
Theory of Operation
1--Left Control Valve--
16--Arm I Valve
29--Arm Head End
37--Left Propel Neutral
5-Spool
17--Arm II Valve
Reduced Leakage
Passage Lift Check
2--Right Control Valve--
18--Arm Regenerative
Relief Valve
Valve
4-Spool
Valve (in Arm II Spool)
30--Arm Head End
38--Rear Pump Control
3--Rear Pump Control
19--Check Valve and
Reduced Leakage
Valve Pilot Inlet Filter
Valve
Orifice (in Arm II
Check Valve
39--Pilot Pressure Signal
4--Flow Combiner Check
Spool)
31--Arm Out Circuit Relief
Passage Filter
Valve
20--Bypass Shut-Off Valve
and Anti-Cavitation
40--Propel Pressure
5--Flow Combiner Valve
21--Swing Valve
Valve
Switch
6--System Relief Valve
22--Arm Rod End Reduced
32--Boom II Power
41--Shuttle Valve
Isolation Check Valve
Leakage Pilot Valve
Passage Lift Check
42--Solenoid Valve
7--System Relief Valve
23--Arm Rod End Reduced
Valve
Manifold
Isolation Check Valve
Leakage Check Valve
33--Auxiliary Power
43--Arm Regenerative
8--System Relief and
24--Swing Lift Check Valve
Passage Lift Check
Solenoid Valve
Power Boost Valve
25--Power Passage-to-Arm
Valve
442--Speed Sensing
9--Left Propel Valve
I Neutral Passage
34--Auxiliary Circuit Relief
Solenoid Valve
10--Right Propel Valve
Check Valve
and Anti-Cavitation
45--Propel Speed Change
11--Auxiliary Valve
26--Arm I Lift Check Valve
Valve
Solenoid Valve
12--Bucket Valve
27--Restriction Orifice (in
35--Front Pump Bypass
46--Power Boost Solenoid
13--Boom II Valve
housing)
Inlet Port
Valve
14--Boom I Valve
28--Arm Head End
36--Propel Flow Control
15--Boom Regenerative
Reduced Leakage Pilot
Valve
Valve (in Boom I
Valve
Spool)
For the location of all valves used in the control valve,
The control valve consists of two monoblock valve
see the three illustrations labeled Left Front, Right
housings called the left control valve (1) and right
Rear, and Bottom and the legends. All valves are
control valve (2). The control valves are mounted
accessible from the outside of control valve by
back-to-back to connect the interconnected oil
removing a plug, cover, or the pilot caps. For line
passages through ports in the mounting faces. The left
connections to the control valves, see the component
control valve is a 5-spool section valve consisting of
9025
location drawings in Group 9025-15. The solenoid
left propel (9), auxiliary (11), boom II (13), arm I (16),
05
valve manifold (42) is located on the front of the
and swing (21). The right control valve is a 4-spool
33
control valve mounting bracket.
section valve consisting of right propel (10), bucket
(12), boom I (14), and arm II (17). Also included in the
The control valve is an open-center valve. Each valve
4-spool section is the bypass shut-off valve (20). The
section controls the flow rate and direction for its
bypass shut-off valve is use to route front pump flow
hydraulic circuit. The rear (3) and front (58) pump
from the right control valve neutral passage, by an
control valves, located in neutral passage of the left (1)
external hose, to the power passage before the
and right (2) control valves, are used to send a pilot
auxiliary valve in the left control valve. Each spool is
control signal to the front and rear pump regulators
selectively fitted to its bore in the housings. The spools
when a function is actuated. (See Pump Control Valve
are moved by pilot oil from the pilot controllers located
Operation in this group.)
in the cab.
Continued on next page
CED,TX08227,3116
1902MAY982/6
6-32
