Fault Phenomenon: Caterpillar D6N dozer a periodic whining sound comes from the rear axle while driving, changing when decelerating.

Troubleshooting Process:
– Checked gears: bevel gear backlash incorrect.
– Checked bearings: bearing preload changed or damaged.
– Checked lubrication: incorrect or insufficient gear oil type.
– Checked housing: housing deformed.

Root Cause: Improper adjustment of the bevel gear backlash and meshing pattern in the rear axle main reducer caused meshing noise.

Required Parts: Main reducer gear set and bearings, readjust.