Hydraulic systems are found across many industries and processes. They vary in size and operate in a very wide range of environments. Factories, trucks, boats, planes, cars, power generation, oil rigs – hydraulic systems can be found all over the place. They are often the workhorse of the plant, but in a lot of cases, hydraulic lubrication is controlled by costs rather than thinking about how key the system is to the overall business.
Most hydraulic system problems are either related to pressure or oil volume. If there is not enough pressure, the machine will not operate properly. Volume related issues will either mean that the pump is not delivering the correct volume of oil, or there is a leak or bypass in the system. If your hydraulic system is running slow, it’s likely a volume issue. It’s important to visually inspect your hydraulic systems as part of your lubrication management routine. By conducting inspections and regularly monitoring the pumps, you should be able to pick up on mechanical issues or leaks before they cause serious issues, or a failure.
If your hydraulic system is making a strange noise, it’s essential that you identify the cause. Cavitation and aeration are common causes of noise. Cavitation produces a constant high-pitched whining sound, while aeration is less frequent and sounds like gravel rattling in the equipment. Cavitation is usually caused by low oil temperatures or a blocked strainer or filter. Aeration is caused by air entering the system usually through a leak in the suction line or a worn seal. Both problems can lead to failure so identifying the cause and sorting the problem is key.
According to Machinery Lubrication, contamination is the cause of approximately 90% of all hydraulic system failures. By using regular oil analysis and the correct filters in your hydraulic system, you can potentially reduce contamination and associated failures. Hydraulic systems usually run at high temperatures, and increased temperature is one of the main catalysts for oil oxidation. By using the correct type and size of filter in your system, and changing them at regular intervals, you will catch many of the particles generated by oxidation or contamination. Filter types include suction filters, pressure line filters and return line filters. Your equipment manufacturer or lubricant supplier should be able to advise the correct type of filters for your system.
The second most common cause of hydraulic failures is overheating. As oil heats up, it starts to degrade and varnish deposits can develop in the system. The oil’s ability to lubricate properly decreases, and component wear starts to occur. By ignoring an overheating hydraulic system, you can allow damage to every part of the system. Finding the cause of overheating can be achieved through inspection and condition monitoring, including thermal imaging. Incorrect pressure settings are a common cause. You may also find that your heat exchanger is not functioning correctly, so you should inspect it too.
Hydraulic oil is often seen as ‘basic’ lubricant, and many businesses purchase based on price rather than quality or benefits. Some hydraulic systems use considerable volumes of oil, so an oil change can be a significant financial outlay. We always advise our customers to weigh up the ‘total cost of ownership’ for their equipment. If you are using a cheap, basic lubricant, but changing it three times as often, and replacing filters and parts more frequently, would you actually be financially better off by switching to a higher quality product? If you are having issues with oxidation or contamination, switching to a higher quality product with anti-oxidation and cleanliness benefits could actually save you money overall. You should also think about thoroughly flushing the system between oil changes if you have contamination issues.
Hydraulic systems are often unappreciated and overlooked when it comes to proactive maintenance, but what would the impact of a system failure be to your business, and can you afford that downtime?