Fault Phenomenon: Caterpillar AP655D paver severe body shudder during transmission shifts.

Troubleshooting Process:
– Checked accumulator: shift accumulator nitrogen leaked.
– Checked oil quality: transmission oil emulsified and deteriorated.
– Checked clutches: friction discs unevenly worn.
– Checked solenoid valves: shift valve response too fast.

Root Cause: The shift accumulator bladder in the transmission ruptured, losing its cushioning effect and causing shift shock.

Required Parts: Replace transmission accumulator bladder and charge with nitrogen.