Fault Phenomenon: Caterpillar 160M grader front axle lock cannot be disengaged, vehicle unable to steer.

Troubleshooting Process:
– Checked cylinder: cylinder action normal.
– Checked control valve: solenoid valve spool stuck in lock position.
– Checked air source: air pressure normal.
– Checked mechanical: lock pin not deformed.

Root Cause: The front axle lock control valve spool is stuck in the lock position due to rust or sludge, unable to switch to the unlock position.

Required Parts: Clean or replace front axle lock control valve.