Fault Phenomenon: JCB telescopic handler during boom extension, a sudden break sound is heard, and the boom cannot fully extend.

Troubleshooting Process:
– Checked telescoping chains: one side chain broken.
– Checked sprockets: sprocket teeth severely worn.
– Checked lubrication: chain ran dry.
– Replaced both chains (must be replaced in pairs) and sprockets.

Root Cause: The chain lacked lubrication for a long time and broke due to fatigue.

Required Parts: Telescoping chain set, sprockets.