Fault Phenomenon: CAT rotary drilling rig a periodic metallic impact sound occurs from the rotary head gearbox during rotation.

Troubleshooting Process:
– Checked gears: planetary gears broken or pitted.
– Checked bearings: bearing cage collapsed or raceway spalling.
– Checked lubrication: insufficient or deteriorated gear oil.
– Checked foreign objects: metal debris jamming gears.

Root Cause: The rotary head gearbox planetary gear broke due to fatigue or poor lubrication, causing impact noise.

Required Parts: Replace rotary head gearbox assembly or gear set.