Sakai SW800-II, Shop Manual

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10-075
TROUBLESHOOTING
3-2. Propulsion
If a problem occurs in the propulsion systems such as the propulsion pump, propulsion motor and brakes,
determine the cause and carry out action as required, according to the following general troubleshooting items.
(NOTICE)
When checking whether or not the pressure is correct, refer to the pressure standard value for each
hydraulic circuit.
3-2-1. Vehicle moves neither forward nor backward 1/2
Check point Cause Check/Action
1. Oil Level of
Hydraulic Oil Tank
Oil level in hydraulic oil tank is low. Fill tank until correct oil level is obtained.
2. Bypass Valve Bypass valve is open. Close bypass valve.
3. F-R Lever Linkage F-R lever linkage is faulty. Check and adjust F-R lever linkage or
replace it if necessary.
4. Propulsion Charge
Circuit Pressure
Propulsion pump does not discharge oil
because charge pressure is low.
Measure charge pressure. If low, check
and adjust charge relief valve or replace it if
necessary.
*1
Charge pressure decreases due to pressure
leakage from pressure override valve (cut-
off valve).
Check and adjust pressure override valve or
replace it if necessary.
Insufficient propulsion charge pump
discharge.
Repair propulsion charge pump or replace it
if necessary.
Charge pressure decreases due to internal
leakage of solenoid valve connecting oil
supply circuit with charge circuit.
Brake release solenoid valve •
When solenoid is energized, check if oil
flows in return circuit to tank. If so, carry out
following action.
Repair or replace brake solenoid valve. •
5. Propulsion Servo
Circuit Pressure
Propulsion pump can not discharge oil
because oil does not flow into servo cylinder
chamber due to a faulty control valve or
linkage.
Measure servo circuit pressure. If low, repair
control valve and linkage or replace them if
necessary.
6. Suction Filter for
Charge Pump
Charge pump flow is reduced due to
clogged filter.
Clean suction filter or replace it if necessary.
7. Propulsion Circuit
Pressure
Pump does not discharge oil because
setting pressure of pressure override valve
(cut-off valve) is low.
Measure propulsion circuit pressure. If low,
check and adjust pressure override valve or
replace it if necessary.
Circuit does not obtain required pressure
because setting pressure of high-pressure
relief valve is low.
Measure propulsion circuit pressure. If low,
check and adjust high-pressure relief valve
or replace it if necessary.
8. Propulsion Motor Internal leakage of propulsion motor. Measure drain quantity from propulsion
motor. If drain quantity is larger than
standard value, repair propulsion motor or
replace it if necessary.
Sticking of disc brakes causes brakes to
remain applied.
Replace disc brakes.
*1: Relief valve for charge circuit is located in propulsion pump.
•