Fault Phenomenon: Komatsu WA380 wheel loader steering wheel is extremely heavy when turning in place, poor power assist.

Troubleshooting Process:
– Checked steering pump: gear pump internal leakage, low pressure.
– Checked priority valve: flow priority valve stuck, insufficient steering flow.
– Checked steering cylinder: cylinder internal leakage or piston rod bent.
– Checked tank: low hydraulic oil level or suction strainer clogged.

Root Cause: The steering priority valve spool is stuck due to debris, causing most of the hydraulic oil to flow to the work equipment, resulting in insufficient steering system flow.

Required Parts: Clean or replace steering priority valve, replace hydraulic oil filter.