4-85
4
CONTROL VALVE
DISASSEMBLY AND ASSEMBLY
Inspection and adjustment
Checking the parts
Parts Criteria Action
Housing, valve body • Scratches,
rust or corrosion on the parts sliding against the
spool
• Scratches,
rust or corrosion on the seal pocket part that
the spool enters
• Scratches,
rust or corrosion on the seal part on the port
that is in contact with the O-ring
• Scratches,
rust or corrosion on the seal part of the relief
valve, etc.
• Other damage consider
ed to impair normal functions
• Replace
• Replace
• Replace
• Replace
• Replace
Spool • Scratches
on the sliding surface of outer circumference, on
which the fingernails get caught
• Scratches
on parts that slide against the seals at both
ends
• Spool does not move smoothly
• Replace
• Replace
• Repair or r
eplace
Load check valve • Imperfect sealing due to damage to the valve or spring.
• Operates
smoothly when inserted and operated in the
housing
• Repair or r
eplace
• Normal
Ar
ound the springs • Rust,
corrosion, deformation, breakage or other notable
damage to the spring, holder or cover
• Replace
Around the spool seal • Oil leakage to the outside
• Rust, corr
osion or deformation of the seal holder
• Repair or r
eplace
• Repair or r
eplace
Main relief valve, port re-
lief
valve, anti-cavitation
valve
• External rust, damage
• Damage to valve seat contact surface
• Damage to poppet contact surface
• Abnormality in the spring
• O-rings, backup rings, seals
• Replace
• Replace
• Replace
• Replace
• Replace as a rule
Adjusting the main r
elief valve pressure
“2. Service data, Performance criteria”
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