Fault Phenomenon: Caterpillar AP555F paver cannot adjust the screed crown, locked in one position.

Troubleshooting Process:
– Checked screw: crown adjustment screw rusted and seized.
– Checked motor: electric actuator motor burnt.
– Checked mechanical: thread wear, stripped.
– Checked control: no output from switch signal.

Root Cause: The trapezoidal screw of the screed crown adjustment mechanism is rusted and seized due to lack of lubrication, and the electric actuator cannot move it.

Required Parts: Derust and lubricate screw or replace electric actuator assembly.