Sakai SV400D-2, Руководство по ремонту

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9-039
HYDRAULIC SYSTEM TROUBLESHOOTING
3-2. Propulsion
If a problem occurs in the propulsion system such as propulsion pump, propulsion motor or
brake, determine the cause and carry out action as required, according to the following general
troubleshooting items.
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
Check point Cause Check/Action
1. Bypass Valve
(unloader valve)
Bypass valve is open. Close the valve.
2. Oil Level of Hydraulic Oil
Tank
Oil level in hydraulic oil tank is low. Fill the tank until the correct oil level is
obtained.
3. Forward/Reverse Lever
Linkage
Forward/reverse lever linkage is faulty. Check the forward/reverse lever linkage,
and then adjust or replace as required.
4. Charge Circuit Pressure Propulsion pump does not discharge oil
because 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
- Speed change 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.
- Repair or replace the solenoid valve.
5. Neutral Solenoid Valve Propulsion pump does not discharge
oil because the spool of the neutral
solenoid valve does not shift. Repair or replace the neutral solenoid
valve if the spool of the valve does not
shift.
6. Suction Filter for Charge
Pump
The charge pump flow is reduced due to
clogged filter.
Clean or replace the suction filter.
7. Pressure in Propulsion
Circuit
The circuit does not obtain the required
pressure because the setting pressure
of relief valve is low. Measure the propulsion circuit pressure.
If low, check multifunction valve, and
then adjust or replace as required.
8. Propulsion Motor Internal leakage of propulsion motor. Measure the drain quantity from
propulsion motor. If the drain quantity is
larger than the standard value, repair or
replace the motor.
9. Brake Release Input
Pressure
The brakes are not released because
the brake release pressure is too low. (1) Measure the brake release inlet
pressure.
(2) Measure the parking brake solenoid
valve inlet pressure when the
solenoid is not energized.
- If above measurement (1) shows low
pressure and (2) is OK, then repair or
replace the brake cylinder.
10. Parking Brake Solenoid
Valve
Brake is still applied because the spool
of the parking brake solenoid valve does
not shift. Repair or replace the brake solenoid
valve.
11. Rear Axle (inside brake) Sticking of the disc brakes causes the
brakes to remain applied.
Replace the disc brake.