Fault Phenomenon: LiuGong 856 wheel loader brake pedal feels very soft, braking force extremely weak, or no brakes.

Troubleshooting Process:
– Checked booster: booster piston cup ruptured or piston stuck.
– Checked air system: insufficient brake air pressure.
– Checked brake fluid circuit: insufficient brake fluid or air in system.
– Checked brake calipers: caliper pistons seized.

Root Cause: The rubber piston cup inside the air-over-hydraulic brake booster ruptured, preventing air pressure from pushing the hydraulic piston and building brake fluid pressure.

Required Parts: Replace brake booster repair kit or assembly, bleed brake system.