Loss Of Pressure; Excessive Or High Peak Pressure; Noise Or Squeal; Erratic Pump (Load/Unload) Cycle - Komatsu 930E-2 Shop Manual

POSSIBLE CAUSES
TROUBLE: Loss of pressure
Defective pressure control
Internal steering pump wear
Excessive leakage in brake system
TROUBLE: Excessive or high peak pressure
Defective or improperly adjusted pressure control(s)
TROUBLE: Noise or squeal
Low compensator or unloader valve setting
Fluid too cold or viscosity too high
Air leak at pump inlet
Insufficient inlet oil supply
Internal pump damage
TROUBLE: Erratic pump (load/unload) cycle
Pressure compensator adjusted incorrectly or defec-
tive
Excessive internal leakage in steering circuit
Unloader valve pilot seat damaged
TROUBLE: Excessive heat
Excessive system pressure
Low hydraulic fluid level
Worn steering or hoist pump
L6-26
Check unloader valve operation and adjust pressure if
necessary. Check compensator adjustment pressure.
Check system relief valves.
Repair or replace pump.
Inspect brake system and check pressures.
Check unloader valve operation and adjust pressure if
necessary. Check compensator adjustment pressure.
Check system relief valves and replace if necessary.
Check pressure and adjust pressure controls.
Warm oil before starting or install proper viscosity oil.
Inspect inlet hose, connections and shut-off valve.
Check hydraulic tank level. Clean suction strainer.
Make certain shut-off valve is open.
Repair or replace pump.
Adjust pressure compensator or repair if necessary.
Check unloader pressure settings.
Measure component leakage rates and replace defec-
tive components.
Replace unloader valve module.
Adjust system pressures
Service hydraulic tank
Repair or replace pump(s).
Steering Circuit Component Repair
SUGGESTED CORRECTIVE ACTION
L06021