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Troubleshooting (Continued)
Problem Cause Correction
Lift, crowd or bucket Problems involving the control Dirt and shreds of packing material are
cylinders drop under load valve (cont.) the usual causes of valve malfunction.
when control spools Be sure the reservoir oil supply is kept
shifted from neutral clean and only factory supplied packing
packings are used in cylinder repair.
Everything must be clean and free of
dirt during the oil line removal and
replacement, and during any cylinder
work.
Load drops or settles Loose oil line connections, Tighten all hose connections and replace
leaks in line or broken lines replace any damaged o-rings at leaking
o-ring fittings. Check and replace any
damaged hoses and lines.
Oil is bypassing cylinder piston, Replace or rebuild the cylinder; replace
scored piston, worn piston damaged parts.
packing, or defective piston
assembly
Worn or damaged rod seals on Repack cylinder. Rebuild cylinder,
cylinder; external leaks replacing damaged parts as necessary.
Worn control valve Replace the control valve.
Damaged or worn spool seals Replace spool end seals.
Leaky cylinders Oil is bypassing cylinder piston, Replace or rebuild the cylinder; replace
scored piston, worn piston damaged parts.
packing, or defective piston
assembly
Scored piston rods and worn Replace or rebuild the cylinder; replace
guides in cylinder damaged parts.
Bent piston rod in cylinder Replace or rebuild the cylinder; replace
damaged parts.
Worn or damaged rod seals on Repack cylinder. Rebuild cylinder,
cylinder; external leaks replacing damaged parts as necessary.
Leaky valve Loose oil line connections, Tighten all hose connections and
leaks in line or broken lines replace any damaged O-rings at
leaking O-ring fittings. Check and
replace any damaged hoses and lines.
Excessive back pressure Relieve condition. Restriction may be
from outlet to reservoir.
Paint on valve spool; sticking Clean valve spool. Binding is usually
valve spool or scored valve caused from an over tightened plug,
spool mounting bolt, fitting in valve body or
tie rod bolt. If a plug or fitting in the
valve body is leaking, do not overtighten
in an effort to stop leak. This will distort
body casting and cause spools to bind.
(cont.)
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