Fault Phenomenon: Palazzani RJA52 telescopic boom aerial work platform going downhill, the exhaust brake has no effect.

Troubleshooting Process:
– Checked butterfly valve: butterfly valve stuck in open position.
– Checked cylinder: cylinder leaking.
– Checked switch: switch failed.
– Checked air lines: air lines leaking.

Root Cause: The exhaust brake butterfly valve shaft is corroded and seized, preventing closure.

Required Parts: Exhaust brake butterfly valve assembly.