Fault Phenomenon: Shantui DH70 drives normally when cold. During heavy-load driving (operating temperature), the driveshaft makes abnormal noise, vibration increases, and eventually breaks.

Troubleshooting Process:
– Checked driveshaft universal joints: well lubricated, no looseness.
– Checked driveshaft dynamic balance: balance weights not missing.
– Checked center support: support rubber not aged, securely fastened.
– Measured driveshaft radial runout at operating temperature: found excessive runout.

Root Cause: Thermal expansion of the driveshaft spline pair causes the fit clearance to disappear, leading to seizure.

Required Parts: Driveshaft assembly.