Fault Phenomenon: Lonking 850 wheel loader (pneumatic shift) sometimes cannot engage gear or automatically disengages after engagement.

Troubleshooting Process:
– Checked pneumatic valve: pneumatic shift valve spool stuck due to oil sludge or moisture.
– Checked air source: insufficient compressed air pressure or presence of water.
– Checked air lines: air line leaking or kinked.
– Checked spring: spool return spring broken.

Root Cause: The pneumatic shift valve spool is stuck due to oil sludge formed by moisture and oil in the compressed air, preventing it from fully shifting.

Required Parts: Clean pneumatic shift valve, install air dryer, or regularly drain air tank.