Fault Phenomenon: XCMG XR360 rotary drilling rig during rotation, the Kelly bar slips, unable to transmit torque.

Troubleshooting Process:
– Checked drive keys: drive keys on the rotary head output flange worn short.
– Checked keyway: keyway elongated and deformed.
– Checked lubrication: lack of grease.
– Checked material: insufficient key material hardness.

Root Cause: The rotary head drive keys are severely worn due to long-term overload operation, causing excessive clearance with the Kelly bar square drive and resulting in slippage.

Required Parts: Replace rotary head drive keys, repair keyway.