Fault Phenomenon: Shantui DH70 steering functions normally when cold. During continuous steering operations (operating temperature), the steering gear leaks oil, steering becomes heavy, and eventually fails.

Troubleshooting Process:
– Checked power steering fluid: level normal.
– Checked steering gear input shaft: shaft not worn.
– Checked oil seal: seal lip intact.
– Measured internal pressure of steering gear at operating temperature: found pressure too high.

Root Cause: The steering gear input shaft oil seal hardens due to heat, causing seal failure and oil leakage.

Required Parts: Steering gear oil seal repair kit.