Fault Phenomenon: Shantui DH80 steering is normal when cold. During in-situ steering (operating temperature), abnormal noise occurs, steering becomes heavy, and eventually fails.

Troubleshooting Process:
– Checked power steering fluid: fluid grade correct, not deteriorated.
– Checked steering pump: pump pressure normal, no leaks.
– Checked steering gear: internal gear meshing normal.
– Measured steering system pressure at operating temperature: found pressure fluctuates.

Root Cause: The recirculating ball nut inside the steering gear expands due to heat, causing sticking.

Required Parts: Steering gear assembly.