Slow Machine Speed Or Small Drive Force 2/2; Machine Speed Cannot Be Switched; Machine Does Not Stop Completely With F-R Lever In "N - Sakai R2-4 Shop Manual

3-2-3. Slow machine speed or small drive force 2/2

Check point
5. Propulsion Motor
6. Propulsion Pump

3-2-4. Machine speed cannot be switched

Check point
1. Speed Change
Solenoid Valve
2. Propulsion Motor
Swash Plate
Stroke Cylinder

3-2-5. Machine does not stop completely with F-R lever in "N"

Check point
1. F-R lever Linkage
2. Servo Control
Valve
3. Propulsion Pump
Servo Cylinder
Cause
Propulsion motor inlet pressure is low.
Propulsion circuit pressure is not held in
propulsion motor case.
Output of propulsion motor decreases and
number of revolutions decreases due to
internal leakage of propulsion motor.
Discharge flow rate is insufficient due to
efficiency degradation of propulsion pump.
Discharge flow rate is insufficient due to
wear of propulsion pump drive shaft splines.
Propulsion circuit pressure is not held in
propulsion pump case.
Cause
Machine speed does not change because
spool of speed change solenoid valve does
not change.
Faulty propulsion motor swash plate stroke
cylinder.
Cause
F-R lever linkage is faulty.
Servo control valve neutral position
adjustment failure.
Faulty propulsion pump servo cylinder or
faulty pump swash plate setting.
TROUBLESHOOTING
Check/Action
• Measure propulsion motor inlet pressure.
• If low, check and adjust multifunction valve
or replace it if necessary.
If pressure in propulsion motor case is not
within allowable range, repair propulsion
motor or replace it if necessary.
• Measure drain quantity from propulsion
motor.
• If drain quantity is larger than standard
value, repair propulsion motor or replace it
if necessary.
• 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.
Replace propulsion pump.
If pressure in propulsion pump case is not
within allowable range, repair propulsion
pump or replace it if necessary.
Check/Action
Repair speed change solenoid valve or
replace it if necessary.
Repair propulsion motor or replace it if
necessary.
Check/Action
Check and adjust F-R lever linkage or
replace it if necessary.
Check and adjust servo control valve or
replace it if necessary.
Repair propulsion pump or replace it if
necessary.
10-069