Fault Phenomenon: Komatsu D155AX dozer wheel lug bolts break while driving, wheel hub becomes loose. (Note: Some models are wheeled)

Troubleshooting Process:
– Checked fracture surface: fatigue fracture characteristics.
– Checked torque: not tightened to specified torque.
– Checked washers: washers missing or deformed.
– Checked wheel hub holes: holes worn oval.

Root Cause: The wheel lug bolts were not tightened to the specified torque and sequence, causing uneven stress and fatigue fracture.

Required Parts: Full set of wheel lug bolts, nuts, and washers.