Sakai SV400D-2, Shop Manual

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9-041
HYDRAULIC SYSTEM TROUBLESHOOTING
3-2-4. Vehicle speed does not change
Check point Cause Check/Action
1. Charge Pressure The propulsion motor swash plate does
not move because the charge pressure
is low. Measure the charge pressure. If low,
check the propulsion or vibrator charge
relief valve, and then adjust or replace
the valve.
Insufficient charge pump discharge
Repair or replace charge pump.
Charge pressure decreases due to
internal leakage of solenoid valve
connecting oil supply circuit with charge
circuit.
- Parking Brake Solenoid Valve When the solenoid is not energized,
check if oil flows in return circuit to
tank. If oil flows, carry out the following
actions.
- Repair or replace the solenoid valve.
2. Speed Change Solenoid
Valve
The vehicle speed does not change
because the spool of the speed change
solenoid valve does not change. Repair or replace the speed change
solenoid valve.
3. Rear Propulsion Motor
Swash-Plate Stroke
Cylinder
The rear propulsion motor swash-plate
stroke cylinder is faulty. Replace the rear propulsion motor.
3-2-5. Vehicle does not stop completely with forward/reverse lever in neutral position
Check point Cause Check/Action
1. Forward/Reverse Lever
Linkage
Forward/reverse lever linkage is faulty. Check the forward/reverse lever linkage,
and then adjust or replace as required.
2. Servo Control Valve Servo control valve neutral position
adjustment failure. Check the servo control valve, and then
adjust or replace as required.
3. Propulsion Pump Servo
Cylinder
Faulty propulsion pump servo cylinder
or pump swash plate setting failure. Replace the propulsion pump.