Fault Phenomenon: Merlo rotating telescopic handler during operation, noticeable play and abnormal noise between the upper body and chassis.

Troubleshooting Process:
– Checked swing bearing bolts: multiple bolts broken or loose.
– Checked swing bearing ring gear: ring gear deformed.
– Replaced all high-strength bolts, tightened to specified torque, replaced deformed ring gear.

Root Cause: Fatigue failure and loss of preload in the swing bearing connecting bolts.

Required Parts: High-strength bolt set, swing bearing.