Fault Phenomenon: Caterpillar AP555F paver conveyor runs continuously, material piles up too high.

Troubleshooting Process:
– Checked spool: height control valve spool stuck in open position.
– Checked linkage: mechanical linkage detached or seized.
– Checked sensor: sensor signal error.
– Checked spring: return spring broken.

Root Cause: The spool of the conveyor height control valve is stuck open by debris, causing the hydraulic motor to run continuously.

Required Parts: Clean or replace height control valve.