The need for hydraulic preventive maintenance is determined over time by operating conditions of the various hydraulic components. For example, a service interval of 10,000 hours (about 14 months) is generally recommended for piston pumps.
The following schedules are intended as guidelines. Experience and operating conditions will determine actual schedules. Refer to OEM datasheets for specific maintenance instructions.
Maintenance tasks: Daily
- Check oil levels in power unit tanks.
- Check for temperature changes in the oil.
- Check the system for water or dirt in the oil.
- Check for leaks.
- Check and tighten screws and pipe clamps.
- Verify pressure gauge readings.
- Monitor the running noise of pumps and electric motors to identify changes.
- Empty all valve panel drip pans.
- Check for possible leaks in valve groups by wiping an item clean before inspecting it.
- Keep surfaces of pipes, components and tanks clean.
- Check with operators to determine if any service or maintenance is required.
- Check the service book to see if operators have recorded any problems.
Maintenance tasks: Every six weeks
- Check air filters.
- For filters with a contamination indicator, replace the filter element when the indicator shows a dirty filter.
- Check and clean the strainer in the cooling water pipe.
- Clean the hydraulic power unit and check for possible leaks.
- Check for possible leaks in the piping connections.
- While the pumps are stopped, tighten any loosened connections. Tighten only to stop the leak and no tighter.
- Replace any fittings or pipes which continue leaking after being tightened. Replace any leaking seals.
- Check the condition of hydraulic hoses. Remove major dirt buildups. If the hoses have cracks or if oil seeps between the sleeve and hose (hose end is moist), replace the hose.
- Check the condition of all hydraulic cylinders. Remove any dirt, especially from piston rod pivots.
- Tighten pipe clamps, if necessary.
- Tighten bolts on the pumps, electric motors, valves, etc.
- Record all maintenance in the service book.
Maintenance tasks: Every six months
- Send an oil sample to the oil manufacturer or a reputable oil testing service to check for contaminants and wear. The oil sample should be analyzed for viscosity, wear metals, particle count and (in hot conditions) the neutralization value.
- If the machine has accumulators, check their pre-charge pressure.
- Check the service book. Write down any recurring problems and carry out any requested maintenance recorded in the book.
Maintenance tasks: Annual
- Drain the power unit oil tank and clean the tank. Carefully remove any dirt accumulated on the bottom of the tank (inside). Thoroughly clean the insides of the tank using a cleaning solution approved by the oil supplier. Do not use cotton waste or cloths when cleaning the tank. If there is a time delay between cleaning and refilling the tank, keep it sealed to prevent moisture from getting inside the tank. Flush the piping.
- If the oil is to be re-used, make sure to drain it into clean containers.
- When re-filling the tank, make sure to filter the new or re-used oil using a separate filter unit.
- Check the pump and motor couplings.
- If the proportional valves require service, notify the component manufacturer or a service engineer authorized by that manufacturer to perform maintenance.
- Check the condition of the hydraulic system by testing all hydraulically actuated components.
For more information on hydraulic maintenance, contact your Valmet representative or check out Valmet's training services.