TM 5-3805-280-24-1
Theory of Operation
1--Left Control Valve
64--Arm II Valve
75--Arm Out Circuit Relief
81--Propel Flow Control
(5-Spool)
65--Boom I Valve and
and Anti-Cavitation
Valve
2--Right Control Valve
Boom Regenerative
Valve
82--Propel Power and
(4-Spool)
Valve
76--Plug
Neutral Passage
56--System Relief Valve
66--Boom Reduced
77--Swing Lift Check Valve
Check Valves (Lift
Isolation Check Valve
Leakage Valve
78--Arm I Power and
Checks)
57--System Relief Valve
67--Bucket Valve
Neutral Passage
83--Rear Pump Control
and Power Boost
68--Right Propel Valve
Check Valves (Lift
Valve
58--Dig Pressure Switch
69--Left Propel Valve
Checks), and
84--Filter and Orifice for
59--Flow Combiner Valve
70--Auxiliary Valve
Restriction Orifice
Pilot Pressure to Rear
Circuit Check Valve
71--Boom II Valve
79--Boom II Power
Pump Control Valve
60--System Relief Valve
71A--Propel-Boom Down
Passage Check Valve
84A--Check Valve and
Isolation Check Valve
Selector Valve
(Lift Check)
Orifice for Propel
61--Propel Pressure
72--Arm I Valve
80--Auxiliary Power
Flow Control Valve
Switch
73--Swing Valve
Passage Check Valve
62--Filter--Pilot Pressure
74--Arm Reduced Leakage
(Lift Check)
Inlet
Valve
63--Solenoid Valve
Manifold
All valves are accessible from the outside of control
The control valve consists of two monoblock valve
valve by removing a plug, cover, or the pilot caps. For
housings called the left control valve (1) and right
line connections to the control valves, see Control
control valve (2). The control valves are mounted
Valve Component and Line Identification in Group
back-to-back to connect the interconnected oil
9025-15. The solenoid valve manifold is also located
passages through ports in the mounting faces. The left
on the right control valve.
control valve is a 5-spool section valve consisting of
left propel (69), auxiliary (70), boom II (71), arm I (72),
The control valve is an open-center valve. Each valve
and swing (73). The right control valve is a 4-spool
section controls the flow rate and direction for its
section valve consisting of right propel (68), bucket
hydraulic circuit. The rear (83) and front (98) pump
(67), boom I (65), and arm II (64). Each spool is
9025
control valves, located in neutral passage of the left (1)
selectively fitted to its bore in the housings. The spools
05
and right (2) control valves, are used to send a control
are moved by pilot oil controlled by the pilot controllers
33
signal to the front and rear pump regulators when a
located in the cab.
function is actuated. (See Pump Control Valve
Operation in this group.) Two pressure switches (58
For the location of all valves used in the control valve,
and 61) located on the front of the control valve are
see the three illustrations labeled Left Front, Right
closed to send an electrical signal to the engine and
Rear, and Bottom and the legends. Also see the
pump controller when a dig or propel function is
Control Valve Circuit Schematic for location of
actuated.
components.
Continued on next page
TX,05,GG2154
1920MAY982/4
6-31
