HYDRAULIC SYSTEM NBT30H-2 SERVICE MANUAL
2-8 03-20-2019 Control # 613-06
PARTS REPLACEMENT
Parts found damaged or out of tolerance when maintenance
is being performed need to be replaced. Refer to the
Manitowoc Crane Care Parts Catalog for proper replacement
parts.
Overheating of hydraulic oil
Wrong operation (running over the load
sense relief pressure setting for long
periods).
Dirty filters.
Oil too light.
Low oil level.
Dirty oil.
Change procedure of operation.
Change filter. See “Hydraulic Filter
Replacement” on page 2-19.
Use correct oil.
Check and add oil.
Change oil and filters. See “Hydraulic
Filter Replacement” on page 2-19.
Foam in hydraulic tank
Leak in system.
Wrong type of oil.
Low oil level.
Bad seal in pump, motor or cylinder.
Check O-ring on pump inlet. Check for
leak in system and correct.
Use correct oil.
Check and add oil.
Overhaul or replace.
Short life of pump bearings,
shafts, etc.
Dirt in oil.
Wrong type of oil.
Change oil and filter more frequently.
Use correct oil.
Pump leakage (external)
Bad seal pump shaft.
Bad seals between pump sections (Swing
& Steering).
Replace shaft seal.
Replace seals.
Difficult to engage valve spools
Restriction in pilot lines.
Dirt or foreign material between valve
spool and valve bore.
Pilot pressure too low.
Broken spring (spool return).
Distortion or damage to valve spool.
Check and correct.
Remove and clean valve spool and bore.
Faulty pressure reducing valve. Replace.
Replace spring.
Replace valve section.
Symptom Possible Cause Remedy
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