18004

Check pump motor operation

Navigate to SINUMERIK Diagnostics > PLC > I/O Status and verify hydraulic pump motor output signal is active. Check actual motor operation and current draw.

Ensure LOTO procedures before checking motor connections

Verify pump pressure output

Install calibrated pressure gauge at pump outlet and compare reading to PLC analog input value in SINUMERIK Diagnostics > PLC > Variable Status.

Check pump manufacturer's pressure vs RPM curve to verify pump performance

Inspect pump coupling and drive

Check motor-to-pump coupling for wear, misalignment, or shear pin failure. Verify pump rotation direction matches manufacturer specification.

Visual leak inspection

Inspect all hydraulic lines, fittings, cylinders, and manifolds for external leakage. Check hydraulic tank fluid level and note any rapid fluid loss.

Hydraulic fluid under pressure can cause injection injuries - depressurize system before inspection

Check cylinder internal leakage

Monitor pressure decay rate with system static. Access SINUMERIK PLC program to review pressure monitoring logic and decay time parameters.

Internal cylinder leakage often shows as slow pressure decay rather than immediate drop

Verify relief valve setting

Check main relief valve setting and operation. Valve may be stuck open or set too low, causing pressure bypass to tank.

Relief valve chatter can cause intermittent pressure loss and false alarms

Test pressure switch operation

Navigate to SINUMERIK Diagnostics > PLC > I/O Status and monitor pressure switch input while manually adjusting system pressure. Verify switch operates at correct setpoint.

Use multimeter to verify switch contacts independent of PLC input status

Calibrate analog pressure transducer

Compare transducer output signal (4-20mA or 0-10V) to actual pressure using calibrated gauge. Check scaling in PLC program and SINUMERIK machine data parameters.

Verify transducer power supply voltage before signal testing

Verify PLC input card function

Test PLC input card by injecting known signal and monitoring response in SINUMERIK PLC diagnostics. Check input card LED indicators and module status.

Swap suspect input to known good channel to isolate card vs field device issues

Review pressure threshold settings

Access SINUMERIK machine data and locate hydraulic pressure monitoring parameters. Compare threshold values to actual system operating pressure requirements.

Threshold should be 10-15% below normal operating pressure to allow for transients

Check debounce timer configuration

Review PLC program logic for pressure monitoring debounce timer. Verify delay time allows for normal pressure fluctuations during actuator cycling.

Too short debounce time causes nuisance alarms, too long delays safety response

Verify analog scaling parameters

If using analog pressure monitoring, check PLC scaling blocks and SINUMERIK analog input configuration to ensure proper pressure value calculation.

Document original parameters before making changes for easy rollback if needed