Fault Phenomenon: Hitachi ZX200 excavator boom sticks when lifting, piston rod visibly bent.

Troubleshooting Process:
– Checked load: boom forced lift against obstacle.
– Checked synchronization: dual cylinder action out of sync.
– Checked material: insufficient piston rod strength.
– Checked guidance: cylinder mounting bracket deformed.

Root Cause: The two boom cylinders moved out of sync, or one side was stuck, causing the cylinder to bear a side load and bend.

Required Parts: Boom cylinder assembly (straighten or replace).