10 U-Type Hydrostatic Unit Service
Troubleshooting
10 - 8
Troubleshooting
Note: Always check all other possible causes of malfunctions listed in the appropriate tractor Service Manual before
troubleshooting the Hydrostatic Unit.
Check Hydro-
static fluid level
OK
Inspect Charge
Check Valves
Repair or
Replace
Fill To Proper
Level
Inspect
Control Linkage
OK
OK
LOW
DIRTY OR CLOGGEDDEFECTIVE
Repair or
Replace
DEFECTIVE
Inspect
Filter
1
Replace
Filter
2
System jerky when starting or operates in one direction only:
System jerky when starting or operates in one direction only:
Check Hydro-
static fluid level
OK
Inspect Charge
Check Valves
Fill To Proper
Level
LOW
Repair or
Replace
DEFECTIVE
Inspect
Filter
Replace
Filter
Repair/Replace
or Clean Fins
Inspect Fan and
Cooling Fins
OK
OK
DIRTY OR CLOGGED
DEFECTIVE OR DIRTY
1
2
OK
Check Charge
Pressure
Unit Still
Operates Hot
Repair/Replace
Hydrostatic
Pump & Moter
OPERATES HOT
Inspect Charge
Pump
Repair or
Replace
Repair or
Replace
Inspect Charge
Relief Valve
OK
OK
DEFECTIVE
DEFECTIVE
OK
Loss of power or system will not operate in either direction:
Check Hydro-
static fluid level
OK
Check Charge
Pressure
Fill To Proper
Level
LOW
Repair or
Replace
Inspect
Filter
Replace
Filter
Repair or
Replace
Check Control
Linkage
OK
OK
DIRTY OR CLOGGED
DEFECTIVE
1
2
OK
Inspect Charge
Check Valves
Unit Still Has
Power Loss
Repair/Replace
Hydrostatic
Pump & Moter
POWER LOSS
Inspect Charge
Pump
Repair or
Replace
Repair or
Replace
Inspect Charge
Relief Valve
OK
OK
DEFECTIVE
DEFECTIVE
OK
LOW
DEFECTIVE
1 If metal particles are found, disassemble and inspect entire Hydrostatic Unit.
2 Always replace filter once it has been removed.
LOW
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