Since hydraulic failures often result in damage to expensive system components, we’ve designed this guide to help you learn the leading causes, and how to prevent most faults before they occur. A little attention to detail and preventive maintenance can go a long way to early fault detection, a safer working environment, and improved uptimes.
Hydraulic failures are a serious and ever-growing problem.
You should always investigate damage left behind after a failure to identify its root cause. That way, you can prevent or minimize hydraulic pump damage in the future.
Studies have shown that 90% to 95% of hydraulic failures are caused by the factors listed below. Although many are related to each other, each has its own specific damage profile.
- Fluid Contamination
Fluid contamination is often the primary cause of hydraulic failures, as it speeds up the rate of wear and tear on the pump. Contamination occurs when foreign material gets mixed into the hydraulic fluid. Foreign materials inside a closed hydraulic system are harmful, and impede operational efficiency.
Contaminants can be in solid, liquid or gaseous form. Improper cleaning of welding burrs breaking off in the system, or the absence of a filter to prevent particles from entering the hydraulic system can also introduce contaminants.
Hydraulic pumps are designed to operate at specific pressure levels. When you subject a pump to pressures higher than its design specs call for, the pressure pushes against the many internal components making up the pump. This over-pressurization can result in greater and faster wearing, and lead to permanent failure.
Aeration pertains to the presence of air bubbles in the hydraulic fluid. When compressed air bubbles are exposed to pressure in the pump, it leads to an implosion effect that can remove metal debris from the pressure plates and raise the local temperature to extreme levels.
- Pump Aeration
Pump aeration happens when air is trapped in the hydraulic fluid, sucked into the pump via leaky inlet joints or faulty shaft seals. It’s marked by a loud, high-pitched sound with the pitch getting higher as the pressure rises. Excessive pump aeration causes the hydraulic fluid to appear milky, and the various components in the hydraulic system to become unstable.
Air bubbles trapped in the hydraulic fluid are subjected to normal hydraulic system pressures. When this occurs, the bubbles can collapse inwardly almost instantly in a violent manner generating intense shock waves. These shock waves can result in serious pump damage.
Cavitation occurs when the hydraulic fluid doesn’t completely fill the existing space in the pump, usually caused by the pump overspeeding, the intake line being too long or too restricted, or abnormally high fluid viscosity. Cavitation produces a high-pitched noise very similar to that of aeration.
- Poor Hydraulic Fluid Viscosity
Fluid viscosity in a hydraulic pump needs to be maintained at a specific level. When the level of viscosity becomes higher than required, it often leads to cavitation. On the other hand, when the level of viscosity is lower than it should be, it can result in too much heat and pump leaking.
- Excessive Heat
Excessive heat is most often a byproduct of other factors causing hydraulic failures, but can also be a trigger. Excessive heat is always a warning sign which should be addressed immediately to prevent further damage.
While hydraulic failures can be attributed to many different factors, most often these failures are related to hydraulic pumps – the component most prone to contamination. When a pump breaks down, it can cause a failure chain reaction in the system.
Many of the known causes of hydraulic pump failures involve using low-quality fluids and contamination. The main thing to remember is that when a hydraulic pump begins to act abnormally, it tends to push debris into its debris field. If a filter is not installed in the downstream, the debris finds its way into the actuators, the valves, and the other components making up the hydraulic system. If left unchecked, this event will lead to damage of these components or the entire system.
The Two Best Steps To Prevent Hydraulic Failures
The most important component in any hydraulic system is the oil. Following these steps will guarantee sustained oil quality and increase your hydraulic system’s lifespan, thereby saving $1000’s in hydraulic equipment repair and replacement costs.
- Filter Your Hydraulic Oil Properly
Hydraulic oil changes should be reserved for when the base oil degrades, or when oil additive depletion has occurred. Make sure your hydraulic oil is being filtered properly to consistently remove contaminants.
- Keep Your Hydraulic Components Cool
The effects of heat events in hydraulic components are cumulative. This means that reduced oil efficiency (i.e., additive depletion and oil oxidation), and damage to components as a result of elevated operating temperatures add up over time.
Gain up to a 10x increase in the meantime between hydraulic failures by simply keeping your hydraulic oil filtered properly, and your hydraulic components operating within recommended temperature ranges.
IOW – Keep it clean, and keep it cool.