GROVE 4-31
CD3340B/YB4411 HYDRAULIC SYSTEM
Published 04/07/2015 Control # 569-00
Main Control Valve
General
The main control valve is designed with very close
tolerances between the spools and the valve bores. Dirt,
chips or sludge can cause these surfaces and seals to wear
and result in internal leakage, sticking spools or both. A
thorough cleaning of the valve and replacement of seals will
generally remedy a leaking problem. Extreme care must be
taken to prevent nicks or scratches in machined surfaces. All
spools must be installed in their original bores. If a spool or
valve bore is damaged, the entire valve section must be
replaced.
Removal
1. Shut off the engine. Before disconnecting the swing or
lift valve section lines or hoses from the main control
valve, let the system bleed down for approximately 10
minutes after shutting off the engine.
NOTE: The swing circuits and lift down circuit will retain
hydraulic pressure for approximately 10 minutes
after the engine is shut down. Do not disconnect
the lines from the valve sections until the pressure
has bled down. Even then, crack each circuit slowly
to release any pressure that might still be in the
circuit.
2. Thoroughly clean the outside of the valve and
surrounding tube lines.
3. Mark for assembly, disconnect and plug all lines and
hoses attached to the valve assembly. Cap all the valve
ports.
4. Loosen and remove the three capscrews, washers and
nuts securing the valve to the mounting plate. Remove
the valve and take it to a clean work area.
Disassembly
Complete Valve Assembly
1. Place the valve assembly on the work bench and
remove all hydraulic fittings.
2. Position the valve with the load sense section (8,
Figure 4-17) facing up.
3. Remove the three nuts (10 and 12) from the studs (9 and
11) at the load sense section (8).
4. Slowly, lift the load sense section from the studs.
NOTE: Be careful when separating the valve sections. The
working sections (2, 4, 5 and 7) have spring loaded
check valve assemblies. The spring could fly out of
the valve section when the section is removed.
5. Slowly, lift the three working valve sections (7, 5, and 4)
from the studs.
6. Slowly, lift the mid-inlet valve section (16) from the studs.
7. Slowly, lift working valve section (2) from the studs.
8. Remove the studs (9 and 11) from inlet section (1).
9. Remove and discard O-rings (24) from the valve
sections.
Spool Section
1. Remove load check spring (25 or 27, Figure 4-18) and
load check poppet (23 or 28).
2. Remove cap assembly (22) by removing the two socket
head capscrews. Remove and discard O-ring (17).
3. On the opposite end, remove the cap assembly (29 or
29A) by removing the two socket head capscrews.
Remove and discard O-ring (17).
Reference Only
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