GROVE 4-7
CD3340B/YB4411 HYDRAULIC SYSTEM
Published 04/07/2015 Control # 569-00
Lift Circuit Troubleshooting
Table 4-2
Telescope Circuit Troubleshooting
Table 4-3
Symptom Possible Cause Remedy
Lift cylinder does not extend or
retract
Control valve not actuated.
Not enough oil from pump to operate the
cylinder.
Bad leak in hydraulic swivel.
Load sense relief valve held open by dirt
on valve seat.
Check hoses to control valve. Also, see
“Difficult to Engage Valve Spools”,
page 4-6.
See “Loss of Movement During
Operation”, page 4-5.
Replace seals.
Disassembly and clean or replace the load
sense relief valve.
Cylinder extends, but does not
retract
Malfunction in holding valve.
Restriction in hose to control valve.
Faulty controller.
Replace the holding valve. DO NOT
ADJUST.
Check and correct.
Repair or replace.
Boom moves slowly downward
when control valve is in
NEUTRAL position
Internal leakage in cylinder.
Leakage in holding valve.
Faulty controller.
Broken centering spring in control valve
section.
Replace piston seals.
Replace holding valve. DO NOT ADJUST.
Repair or replace.
Replace broken spring.
Symptom Possible Cause Remedy
Cylinder will not extend the
boom under load
Restriction in boom sections.
Load too heavy.
Faulty pump.
Leakage in hydraulic swivel.
Load sense relief valve malfunction.
Dirt or restriction in main relief.
Clean and apply lubricant to boom slides.
See Maintenance, page 5-1.
Reduce load.
Overhaul or replace.
Replace seals in the swivel.
Check load sense relief pressure.
Disassembly the relief valve and clean.
Boom extends, but will not
retract
Restriction in hose to control valve.
Malfunction in the holding valve.
Faulty controller.
Check and correct.
Replace the holding valve. DO NOT
ADJUST.
Repair or replace.
Boom slow at extending
Restriction in boom sections. Clean and lubricate boom slides. See
Maintenance, page 5-1.
Boom constantly getting out-of-
sequence
Chain stretch or broken. Adjust or replace chain.
Reference Only
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