Fault Phenomenon: Komatsu WA380 wheel loader when starting, the starter motor spins at high speed but the engine flywheel does not turn, accompanied by a harsh friction sound.

Troubleshooting Process:
– Checked one-way clutch: the one-way clutch in the motor drive gear is worn and slipping.
– Checked flywheel: flywheel ring gear missing teeth or worn.
– Checked solenoid switch: insufficient solenoid travel.
– Checked battery: sufficient battery power.

Root Cause: The roller-type one-way clutch in the starter motor drive gear is worn, unable to lock and transmit torque during starting.

Required Parts: Replace starter motor one-way clutch or motor assembly.