Applicable Systems
9R Tractor
Symptoms
Steering becomes heavy at low engine RPM; normal at high RPM.
Possible Causes
- Steering pump flow insufficient due to worn vanes.
- Steering orbitrol valve internal leakage.
- Steering cylinder rod seal bypassing on one side.
Troubleshooting Steps
- Step 1: Measure steering pump flow at 1000 engine RPM.
Flow ≥ 38 L/min at 1000 RPM. - Step 2: Check steering effort with spring scale at wheel rim.
Effort ≤ 75 N at idle RPM. - Step 3: Inspect steering cylinder for oil weep at rod gland.
No visible leakage past wiper seal.
How to Reset
Replace steering pump or orbitrol; reseal steering cylinder if leaking.
Common Replacement Parts
- Steering Pump RE239222: Steering Pump RE239222
- Orbitrol Valve RE174051: Orbitrol Valve RE174051
Frequently Asked Questions
- Q: Is heavy steering safe to operate?
No, emergency steering may be impossible if pump fails completely.
- Q: What oil viscosity for cold climates?
Use JD Hy-Gard Low-Viscosity for temperatures below -20°C.
Source: John Deere 644K Loader Hydraulic Manual
Category: Heavy Equipment