Sakai SW880-1, Shop Manual

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11-208
TROUBLESHOOTING
3-2-1. Machine moves neither forward nor backward 2/2
Check point Cause Check/Action
9. Propulsion Pump Discharge flow rate is insufficient due to
efficiency degradation of propulsion pump.
Measure discharge flow rate of propulsion
pump with flow meter.
If discharge flow rate is not within specified
range, repair propulsion pump or replace it
if necessary.
•
•
Discharge flow rate is insufficient due to
wear of propulsion pump drive shaft splines.
Replace propulsion pump.
Propulsion circuit pressure is not held in
propulsion pump case.
If pressure in propulsion pump case is not
within allowable range, repair propulsion
pump or replace it if necessary.
10. Parking Brake
Solenoid Valve
Brake remains applied because spool of
parking brake solenoid valve does not shift.
Repair parking brake solenoid valve or
replace it if necessary.
11. Brake Inlet
Pressure
Brake cannot be released because brake
inlet pressure is low.
Measure brake release pressure.
If low, repair or replace propulsion motor.
•
•
12. Flange Drive torque is not transmitted to pump due
to faulty flange.
Replace flange.
3-2-2. Machine moves in one direction only (forward or backward)
Check point Cause Check/Action
High Pressure Relief
Valve
Low circuit pressure due to incorrect high
pressure relief setting or internal leakage
of high pressure relief valve.
• Interchange two high pressure relief
valves.
If faulty condition is accordingly reversed,
check and adjust high pressure relief valve
or replace it if necessary.
•
•
3-2-3. Slow machine speed or small drive force 1/2
Check point Cause Check/Action
1. Bypass Valve Bypass valve is slightly open. Close bypass valve completely.
2. Propulsion Charge
Circuit Pressure
Stroke of propulsion pump swash plate
is small because charge pressure is low,
decreasing discharge rate of propulsion
pump.
Measure charge pressure.
If low, check and adjust charge relief valve
or replace it if necessary.
•
•
Insufficient steering • charge pump
discharge.
Repair steering • charge pump or replace it
if necessary.
Charge pressure decreases due to internal
leakage of solenoid valve connecting oil
supply circuit with charge circuit.
Parking brake solenoid valve •
When solenoid is energized, check if oil
flows in return circuit to tank.
If oil is flowing, repair solenoid valve or
replace it if necessary.
•
•
3. Suction Filter for
Steering • Charge
Pump
Flow rate of steering • charge pump
decreases as well as charge pressure
decreases due to clogged filter.
Clean suction filter or replace it if necessary.