Fault Phenomenon: CAT rotary drilling rig engine runs normally, but all hydraulic actions fail.

Troubleshooting Process:
– Checked coupling: elastic coupling spider shattered or shaft broken.
– Checked spline: spline shaft worn.
– Checked alignment: poor engine-pump alignment.
– Checked vibration: excessive start-up shock.

Root Cause: The elastic coupling between the engine and main hydraulic pump broke due to fatigue or overload, preventing power transmission to the hydraulic pump.

Required Parts: Replace hydraulic pump drive coupling assembly.