Textron JACOBSEN GP400, Technical/Repair Manual

Page: 148 / 354

5-30 4252490-Rev A
HYDROSTATIC POWER TRAIN
5
Troubleshooting
Mower Will Not Move Forward or Reverse
Mower Will Not Reach Full Speed
Mower Moves When Traction Pedal Is in Neutral
Probable Cause Remedy
Hydraulic oil not at correct level in reservoir. Fill reservoir to correct level. (Refer to “Parts and Maintenance
Manual” for correct oil specifications.)
Tow valve open. Close tow valve. (Refer to “Safety and Operation Manual.”)
Low charge pressure. Test charge pressure relief valve. (See “Charge Pressure Test” on
page 5-36.) Repair or replace charge pressure relief valve as
needed. (See “Traction Pump and Control” on page 5-50.)
Front wheel motor worn or damaged. Test motor. (See “Wheel Motors Tests” on page 5-43.) Repair or
replace motor as needed. (See “Wheel Motors” on page 5-57.)
Rear wheel motor worn or damaged. Test motor. (See “Wheel Motors Tests” on page 5-43.) Repair or
replace motor as needed. (See “Wheel Motors” on page 5-57.)
Traction pump worn or damaged. Test pump. (See “Traction System Test” on page 5-37.) Repair or
replace pump as needed. (See “Traction Pump and Control”
on page 5-50.)
Probable Cause Remedy
Hydraulic oil not at correct level in reservoir. Fill reservoir to correct level. (Refer to “Parts and Maintenance
Manual” for correct oil specifications.)
Tow valve open. Close tow valve. (Refer to “Safety and Operation 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.
Low charge pressure. Test charge pressure relief valve. (See “Charge Pressure Test” on
page 5-36.) Repair or replace charge pressure relief valve as
needed. (See “Traction Pump and Control” on page 5-50.)
Traction pump worn or damaged. Test pump. (See “Traction System Test” on page 5-37.) Repair or
replace pump as needed. (See “Traction Pump and Control”
on page 5-50.)
Front wheel motor worn or damaged. Test motor. (See “Wheel Motors Tests” on page 5-43.) Repair or
replace motor as needed. (See “Wheel Motors” on page 5-57.)
Rear wheel motor worn or damaged. Test motor. (See “Wheel Motors Tests” on page 5-43.) Repair or
replace motor as needed. (See “Wheel Motors” on page 5-57.)
Engine RPM low. Verify and adjust engine RPM. (See engine manufacturer’s
manual for further instructions.)
Probable Cause Remedy
Traction pump neutral not properly adjusted. Adjust traction pump neutral. (See “Neutral Adjustment” on
page 5-32.)