Quick engineering answer
Abnormal clinker-cooler hydraulic pressure is a symptom, not a diagnosis. Verify the pressure signal, oil condition and common hydraulic supply, then compare circuits and stroke position. High pressure that repeats at one physical position usually points toward mechanical resistance; low pressure across all circuits points toward the common supply path.
Confirm pressure indication, oil level, temperature and filter condition.
Compare all circuits and identify whether the fault is common or local.
Check pumps, valves, hoses, cylinders, pins, bearings and frame movement.
Repeat the operating sequence after correction and compare pressure and stroke behavior.
Start with measurement
Compare the control-system pressure with a known-good local indication where the design allows it. Confirm the pressure transmitter, scaling and isolation arrangement before changing hydraulic settings.
Low hydraulic pressure
Check oil level, oil temperature, suction restriction, filter condition, pump operation and external leakage. A relief valve bypassing too early can also prevent the circuit from reaching normal pressure. If the pressure is low only during movement, compare pump flow and cylinder demand under load.
High hydraulic pressure
High pressure can indicate excessive mechanical resistance rather than a hydraulic-unit fault. Inspect the cooler drive mechanism, cylinders, pins, bearings, frame alignment and moving grate components for binding or abnormal load. Also verify control-valve operation and the approved pressure settings before changing any relief adjustment.
Unstable or oscillating pressure
Pressure oscillation can come from aerated oil, unstable pump control, accumulator problems, a sticking valve, intermittent mechanical resistance or a bad pressure signal. Trend pressure together with cylinder position, cooler stroke, oil temperature and alarms to identify whether the event repeats at the same mechanical position.
Separate hydraulic faults from mechanical resistance
If pressure rises at the same point in every stroke, inspect the mechanical load at that position. If all circuits are low, focus on common hydraulic supply. If one circuit alone is abnormal, compare its valve, hose, cylinder, sensor and local mechanics with the healthy circuits.
Oil condition and filtration
Check oil cleanliness, water contamination, temperature and filter condition. Oil that is too cold or too hot can change system response. A restricted filter can also affect available flow even when static pressure appears normal.
Practical troubleshooting sequence
- Verify pressure indication.
- Record oil temperature and level.
- Check filters and pump supply.
- Look for visible leakage.
- Compare pressure by circuit and stroke position.
- Inspect cylinders, pins, bearings and moving frame alignment.
- Review valve commands and alarms.
- Compare the trend with a known-good operating period.
Do not increase a pressure setting to overcome a mechanical restriction. That can move the symptom while increasing load on cylinders, piping and mechanical components.
Field decision matrix
| Observed pattern | Most useful next check | Do not do first |
|---|---|---|
| All circuits low, especially during motion | Verify pump inlet condition, filter restriction, pump output and common relief path | Increase relief setting |
| One circuit low while others are normal | Compare that valve, hose, cylinder leakage and pressure signal with a healthy circuit | Condemn the main pump |
| Pressure peaks at the same stroke position | Inspect pins, guides, bearings, cylinder geometry and frame/grate resistance at that position | Treat the peak as random hydraulic noise |
| Pressure oscillates with foamy oil | Check suction leaks, reservoir level, return condition and air ingress | Keep cycling the cooler under full load |
Shutdown inspection and acceptance logic
Before opening the hydraulic circuit, capture a short baseline: pressure by circuit, oil temperature, commanded and actual stroke position, cycle time and any filter or accumulator alarms. This prevents the team from losing the fault signature after shutdown. During inspection, compare cylinder rod condition, pin freedom, hose condition, valve leakage and mechanical resistance between equivalent cooler lanes. After corrective work, repeat the same operating sequence at comparable clinker load and confirm that pressure, cycle time and stroke profile have returned toward the known-good baseline.
A repair should not be accepted only because the alarm disappeared. Accept it when the pressure signal is credible, the affected circuit completes its commanded motion without abnormal peaks, oil temperature remains controlled, and the mechanical movement is free through the complete stroke. If pressure remains high only at one physical position, stop hydraulic tuning and return to mechanical inspection.
Escalation checklist
- Stop and escalate if a hose, fitting or cylinder shows active leakage or structural damage.
- Investigate repeated filter restriction instead of repeatedly replacing elements without contamination analysis.
- Do not alter accumulator pre-charge or relief settings without the OEM procedure and safe isolation.
- Record before/after pressure trends so the next shutdown can distinguish deterioration from normal load variation.
Reference basis
FLSmidth’s cement services catalogue includes hydraulic pressure data logging, oil particle counting, pump checks, accumulator checks, piping and valve inspection, cylinder function and cooler-frame alignment as part of cooler hydraulic-system inspection.