5-20 673831-Rev A
HYDROSTATIC POWER TRAIN
5
Troubleshooting
Mower Will Not Move Forward or Reverse
Mower Will Not Reach Full Speed
Probable Cause Remedy
Hydraulic oil not at correct level in reservoir. Fill reservoir to correct level. (Refer to “Safety, Operation, and
Maintenance Manual” for the correct oil specifications.)
Bypass valve open. Close bypass valve. (Refer to “Safety, Operation, and
Maintenance Manual.”)
Low charge pressure. Test charge pressure relief valve setting. (See “Charge Pressure
Test” on page 5-25.) Repair or replace charge pressure relief
valve as needed. (See “Traction Pump” on page 5-40.)
Gear pump damaged. Test and repair. (See “Charge Pressure Test” on page 5-25.)
Front wheel motors worn or damaged. Test motors. (See “3WD System Test” on page 5-31.) or (See
“4WD System Test” on page 5-35.) Repair or replace motor as
needed. (See “Front Wheel Motor” on page 5-47.)
Traction pump worn or damaged. Test pump. (See “Traction Pump Tests” on page 5-29.) Repair or
replace pump as needed. (See “Traction Pump” on page 5-40.)
Damaged traction linkage. Repair traction linkage. (See “Traction Pedal” on page 9-6 and
“Traction Linkage” on page 5-68.)
Probable Cause Remedy
Hydraulic oil not at correct level in reservoir. Fill reservoir to correct level. (Refer to “Safety, Operation, and
Maintenance Manual” for the correct oil specifications.)
Bypass valve open. Close bypass valve. (Refer to “Safety, Operation, and
Maintenance Manual.”)
Air in hydraulic system (air bubbles in hydraulic oil). Check suction line for air leaks. Repair as needed. Operate
various hydraulic systems until hydraulic system is free of air.
Speed stops not properly adjusted. Adjust speed stops. (See “Speed Stop Adjustments” on
page 5-22.)
Low charge pressure. Test charge pressure relief valve setting. (See “Charge Pressure
Test” on page 5-25.) Repair or replace charge pressure relief
valve as needed. (See “Traction Pump” on page 5-40.)
Gear pump worn or damaged. Test gear pump. (See “Charge Pressure Test” on page 5-25.)
Repair or replace gear pump as needed. (See “Gear Pump” on
page 6-49.)
Traction pump worn or damaged. Test pump. (See “Traction Pump Tests” on page 5-29.) Repair or
replace pump as needed. (See “Traction Pump” on page 5-40.)
Front wheel motors worn or damaged. Test motors. (See “3WD System Test” on page 5-31.) or (See
“4WD System Test” on page 5-35.) Repair or replace motor as
needed. (See “Front Wheel Motor” on page 5-47.)
Engine RPM low Verify and adjust engine RPM. (See engine manufacturer’s
manual for further instructions.)
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