Hydraulic System - Komatsu 06253 Operation & Maintenance Manual

OPERATION

3.25.2 HYDRAULIC SYSTEM

Problem
Poor hydraulic system perfor-
mance
Excessive oil temperature
Jerky motion of power cylinders
Noise when slewing
Excessive oil foaming
Hydraulic oil not at operating temperature.
Engine speed too low.
Reservoir low on oil
Restrictions in lines
Cooling circuit, pump control system and/or pilot control circuit
defective.
Internal leakage (control blocks, valves or power units.)
Pressure lines twisted or kinked
Spool not in full stroke.
Relief valve defective, or out of adjustment.
Worn cylinders.
Defective hydraulic pump.
Low oil level
Incorrect viscosity or type of oil
Hydraulic oil cooler clogged with dirt.
Oil cooler fan defective or wrong speed.
Cooling circuit defective
Pump control system defective
Spool not in full stroke.
Internal leakage (control blocks, valves or power units)
Worn pump components
Job conditions (high temperature of materials being handled)
Piston rod bent
Piston sticking
Inside diameter of cylinder tube partially increased or scored
Air in control circuit
Oil too cold
Valve spool sticking, centering springs defective
Pump and/or engine control system defective
Valve of power circuit defective
Insufficient lubrication of swing ring gear and/or slewing connection.
Slewing connection mounting bolts loose
Drive pinion worn
Swing gear bearings worn
Sun gear or planetary pinions worn
High pressure circuit valves defective
Anti-cavitation valves sticking
Air in hydraulic system
Poor quality oil
Excessive by-passing of oil over relief valves
Pressure hoses badly twisted or kinked
Restricted oil flow due to foreign matter
Breather on the reservoir clogged.
Relief valve improperly adjusted
3.25 TROUBLE SHOOTING
Probable cause
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