Inspection and analysis: maintenance personnel inspect vehicle chassis, visual steering machine and front suspension. Check the ball joints, no damage to the dustproof sleeves and no oil leakage. Check the bolts of all places, and no loosening is found. The front wheel was swung hard, and a slight "click" was found, which was consistent with the fault. Inspection found that there was a gap between the steering gear and its fixing device. The tightening force of the nut of the fixing device is increased. It is determined that abnormal wear has occurred in the steering gear fixing device. Troubleshooting: replacing steering gear fixing device and troubleshooting.