Approximately 80% to 90% of all hydraulic equipment failures are caused by air or water contamination, or excessive heat. Faulty pumps, temperature issues and system breaches (loss of fluid pressure most often caused by leaks or burst hydraulic hose) can each be a root cause of contamination.
The hydraulic pump is literally the heart of the machine, and its failure can be extremely damaging. When a pump fails it means costly downtime and expensive repairs. In addition to repair costs, every hour heavy machinery or industrial equipment is off-line can be more costly to the organization than the repairs. That’s why scheduled preventative maintenance is so important. The sooner a pump problem is recognized the easier and less expensive it will be to fix.
Warning Signs of Impending Pump Failure
Because the hydraulic pump is at the heart of the machine it is also the workhorse that can’t be neglected. It is the single component most subject to wear and most likely to cause a gradual or sudden failure of the hydraulic system.
It’s important to recognize the following symptoms of a potential hydraulic pump failure:
- Erratic cylinder operation
- Knocking and banging sounds
- Leaking hydraulic fluid
- Pump seals that frequently fail, usually due to a bent or misaligned rod
- Sudden drop in pressure
- Unusual vibration
- Unusually high system temperature while the pump is running (pumps should never exceed 180°F (82°C) under normal working conditions)
- Weak hydraulic motor with a planetary gear system (a.k.a. final drive motor)
These symptoms do not always prove that the hydraulic pump is failing, however it does mean something in the hydraulic system is about to fail if gone unchecked. With contamination being a primary cause of most pump failures, preventing contamination is a reasonably clear-cut process that can save hundreds, if not thousands, in repair and replacement costs. Not to mention the often higher costs associated with downtime.
Take Caution When Working on Hydraulic Systems
The danger in working on hydraulic systems is they are under high pressure, typically 2,000 PSI or more, and are also at high temperature. When performing maintenance there is the potential of being exposed to three kinds of hazards:
- Cuts, bruises, or even fractured limbs caused by flailing hydraulic hose.
- Burns from hot/high-pressure fluid.
- And the most extreme - hydraulic injection of fluid into the skin. Hydraulic injection initially feels like a bee sting and is too often ignored. However, within a few hours the symptoms turn to higher levels of pain, swelling, and redness. Then numbness and throbbing rapidly move into the affected area. If the injury goes untreated, within about six hours hydraulic fluid can easily cause compartment syndrome, where necrotic tissues cause cells to die, which can result in amputations, and even death.
Therefore, the first step is to release the pressure before adjusting or removing components.
Some systems store hydraulic energy in accumulators which are designed to store oil under pressure when the engine is shut down, the hydraulic pump can’t keep up with demand, or the pump malfunctions. Even if a component is disconnected, or the pump has stopped, the system is still under pressure. Consequently, it’s imperative to relieve the pressure before the work begins.
Knowing When There’s an Issue with the Hydraulic System
Preventative maintenance is a given when it comes to any machine or system, from changing the oil in a car to servicing a hydraulic system in everything from a backhoe to an airplane. But knowing the signs of hydraulic problems and what to do about them is critical to avoid impending system failure.
As mentioned, heat, air and water contamination are the most common causes of impeded hydraulic performance. The hydraulic pump is the most critical component in the system and the most expensive to replace. As a pump begins to wear, debris are usually introduced into the system. These can be metal chip debris or even hydraulic fluid foaming. Foaming is an often overlooked issue with industrial machinery, where a collection of small bubbles of air accumulates on or near the surface of the fluid leading to excessive oxidation, cavitation, and the reduction of lubricating properties. Any of these issues can ultimately cause hydraulic system failure or at the very least downstream issues.
Common Solutions for Hydraulic Problems
Repairing leaks, maintaining the correct fluid levels, and using proper filtration all add up to the first line of defense against hydraulic system contamination and excessive heat. It’s vital to use the correct fluid as recommend by the OEM manufacturer in hydraulic pumps and systems and keep the system clean and free of air and water.
Synthetic and Semi- Synthetic hydraulic oils improve efficiency and provide exceptional protection in extreme heat and cold. These fluids also offer increased resistance to oxidation that can result from heat with the addition of special inhibitors. They are formulated with anti-wear additives to help prevent hydraulic pump and valve wear while providing added protection in severe conditions. In addition, the inclusion of anti-foam additives in the fluid helps in releasing air from the system.
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