Fault Phenomenon: Caterpillar AP655D paver screed tamper frequency cannot be increased, pre-compaction low.

Troubleshooting Process:
– Checked flow valve: tamper circuit flow restrictor set too low.
– Checked motor: motor internal leakage severe.
– Checked pump: pump displacement insufficient.
– Checked load: mechanical binding.

Root Cause: The flow control valve in the screed tamper hydraulic circuit is set too low, limiting the flow to the motor and preventing it from reaching the required speed.

Required Parts: Readjust flow control valve.