Fault Phenomenon: SANY SY5418THB reversing is smooth when cold. During high-frequency reversing (operating temperature), the reversing impact is strong, lines vibrate, and eventually oil leaks.

Troubleshooting Process:
– Checked accumulator pressure: nitrogen pressure normal.
– Checked reversing valve: spool moves freely.
– Checked electrical signals: reversing signals synchronized.
– Measured reversing cushion pressure at operating temperature: found cushion pressure ineffective.

Root Cause: The reversing cushion valve spool sticks due to heat, failing to provide cushioning.

Required Parts: Reversing cushion valve assembly.