Most Common Causes of Hydraulic Systems Failure
Author: Michele Baker Ph.D
When a hydraulic system fails, finding the source of the problem can be a challenge. Hydraulic systems primarily consist of a pump, reservoir, lines, valves, actuators, and hydraulic fluid, and any of these parts could be the source of failure. That is not to mention the additional potential for failure through human error and faulty maintenance practices. If your system fails, you need to know why it fails, how to find the failure, and how to keep it running smoothly in the future all while keeping personnel safe. First, we’ll discuss common causes of failure. Then we’ll offer some proven solutions.
Table of Contents
Common Causes of Hydraulic Failure
It is often easy to tell when a hydraulic system fails — symptoms can include high temperatures, low-pressure readings, and slow or erratic operation. Still, what are the most common causes of hydraulic system failures? We can trace most hydraulic issues back to a few common causes.
1. Air and Water Contamination
Air and water contamination are the leading causes of hydraulic failure, accounting for 80 to 90% of hydraulic failures. Faulty pumps, system breaches, and temperature issues often cause both types of contamination.
Air contamination is the entrance of air into a hydraulic system and consists of two types — aeration and cavitation. Both can cause severe damage to the hydraulic system over time by wearing down the pump and surrounding components, contaminating hydraulic fluids, and even overheating the system. Although we are not pump manufacturers, we know it is essential to be aware of these types of contamination and how to identify their symptoms.
- Cavitation: Hydraulic oil consists of about 9% dissolved air, which the pump can pull out and implode, causing pump problems and damage to the pump and to other components in a hydraulic system over time. You can identify this problem if your hydraulic pump is making a whining noise.
- Aeration: Aeration occurs when air enters the pump cavity from an outside source. Usually, loose connections or leaks in the system cause this issue. Aeration also creates a sound when the pump is running, which sounds like knocking.
Water contamination is also a common problem in hydraulic systems, often caused by system leaks or condensation due to temperature changes. Water can degrade hydraulic components over time through oxidation and freeze damage. A milky appearance in hydraulic fluid can help you identify water contamination.
2. Temperature Problems
Hydraulic systems that run too hot or too cold can cause severe problems over time. Some of these challenges include the following symptoms.
- Fluid thinning: Heat can cause hydraulic fluids to thin, preventing proper lubrication and making the fluid more likely to leak.
- Fluid oxidization: Extreme heat can cause hydraulic fluid to oxidize and thicken. This fluid thickening can cause buildups in the system that restrict flow but can also further reduce the ability of the system to dissipate heat.
- Fluid thickening: Low temperatures increase the viscosity of hydraulic oil, making it harder for the oil to reach the pump. In most systems, putting them under load before the oil reaches 70 degrees or more can damage the system through cavitation.
Poor heat dissipation is the usual suspect behind heat buildup, while environmental factors most often cause too-cool systems.
3. Fluid Levels and Quality
Fluid levels and quality can affect hydraulic system performance. Low fluid levels and inappropriate filtration can result in air contamination, while fluid contamination can cause temperature problems. Leaks can further exacerbate both issues.
Using the correct type of fluid is also essential, as certain hydraulic oils are compatible with specific applications. There are even oil options that offer higher resistance to temperature-related problems. Some oils even offer anti-wear and anti-foam additives to help prevent wear and air contamination, respectively.
4. Human Error
Human error is the base cause of many hydraulic system problems. Some of the most common errors that may result in your hydraulic pump not building pressure include the following.
- Faulty installations: Improper installation of any component in a hydraulic system can result in severe errors. For example, the pump shaft may be rotating in the wrong direction, negatively affecting pressure buildup, or hydraulic lines may be incorrectly fitted, resulting in leaks.
- Incompatible parts: An inexperienced installer may put mismatched components together, resulting in functional failures. For example, a pump may have a motor that runs beyond its maximum drive speed.
- Improper maintenance or usage: Using systems outside their operational capabilities or failing to perform regular maintenance are some of the most common causes of hydraulic system damage but are easy to rectify through updated maintenance policies and training.
Hydraulic System Troubleshooting
The sources of system failures can be tricky to identify, but some hydraulic troubleshooting steps can help narrow down the options. So how do you troubleshoot a hydraulic system? Here are some of the fundamentals.
- Check the motor: Ensure the motor has the correct wiring and can turn on and off.
- Check the pump: Take the pump assembly apart and assess all parts to ensure that they are functional and installed correctly. The most common problem areas include the pump shaft, coupling, and filter.
- Check the fluids: Check the level, color, and viscosity of the hydraulic oil to ensure it meets specifications and has not become contaminated. Low hydraulic fluid symptoms include pressure or power loss. When in doubt, drain and replace the fluids.
- Check the seals: Look for evidence of any fluid leakage around your hydraulic system's seals. Leakage can indicate worn-out or blown seals that can cause malfunctions with pumps and control valves.
- Check the filters: Ensure filters are clear of plugs and blockages. Common clogged hydraulic filter symptoms include sluggish or noisy operation.
- Check valves and lines: Observe all lines for potential leaks and tighten every connection point. Also, check the relief valve for any signs of damage.
- Run the system: When you have completed all these essential checks, turn on the system and monitor it for pressure and temperature fluctuations, as well as abnormal sounds. If all seems well, check your pressure sensor for potential failure.
How to Solve Common Hydraulic Problems
So if your system is not functioning properly, how do you solve hydraulic problems? Start your diagnosis with the symptoms you notice.
1. The System Does Not Operate, Runs Too Slowly or Quickly, or Performs Unpredictably.
Common fixes for these issues include:
- Use the specified fluid amount, type, and viscosity by reviewing your manual and replacing or topping off as necessary.
- Check for oil leaks or line blockages, secure all fittings, and clean or replace lines if needed.
- Allow for the recommended system warm-up time to achieve proper oil viscosity and temperature.
- Check and clean or replace clogged or dirty filters.
- Repair or swap out leaking hydraulic lines.
- Verify pressure compensator settings on variable displacement pumps and pressure relief valves.
- Clean dirty components and fix or change out any you notice with excessive wear.
- Check pump drive belts and hardware for correct alignment and tension.
- Verify you are operating within your equipment's load limits and manufacturer-recommended operating speeds.
- Adjust restrictors and relief valves accurately as indicated in your owner's manual.
2. The Oil Foams or Overheats.
Typical fixes for these issues include:
- Ensure the oil is clean, full and of the recommended type.
- Confirm you have the correct reservoir size and cleanliness, and clean or replace if needed.
- Check the oil cooler for proper operation and fix or change it out as needed.
- Confirm that engine speed is within the suggested manufacturer limits.
- Clean, repair or replace clogged or leaking filters and lines.
- Place the control valve in neutral when idle.
3. The Control Valve Binds, Drops Load or Leaks.
There are ways to eliminate these issues, such as:
- Replace worn cylinder fittings and seals.
- Verify linkage and repair spool binding.
- Ensure proper valve alignment and swap out worn or damaged valves.
- Adjust the tension on tie bolts and bracket screws.
- Replace any components with visible cracks or other damage.
4. The Cylinder Leaks, Knocks or Lowers Incorrectly.
To fix these common hydraulic problems, you want to:
- Replace any rods and seals with noticeable damage or wear.
- Verify your load check is functioning and install a new one if needed.
- Check for air in your fluids and remove it or replace leaking lines.
- Swap out the packing and center the actuator.
- Replace leaking cylinder seals.
- Verify valve type is correct for load and use manufacturer-recommended valves.
How to Prevent Hydraulic System Failure
York Precision Machining & Hydraulics has addressed a number of these common performance issues in the proven design and performance of its Bear-Loc® hydraulic load control and locking solution.
- Fail-safe control and load-holding. The Bear-Loc’s® unique positive locking design based on the principles of interference fit and elastic expansion of metals under pressure—the rod is larger than the sleeve—is functionally fail-safe. It locks instantly when pressure is removed, whether accidentally or on purpose. When pressure is applied, the sleeve expands, allowing free movement. Bear-Loc® holds its load, even in the event of unforeseen power loss and/or operator error.
- Unparalleled durability. Most other load-control devices eventually wear and are at risk of dropping loads. The Bear-Loc® design does not depend on moving parts, valves, or other components to obtain or maintain its positive lock. When operated according to its manufactured instructions and rating, there is little or no wear. Bear-Loc lasts for years, even decades. For extreme conditions (such as heat, sand, salt water, to name a few) we are experienced in designing Bear-Loc® with materials and coatings that will stand up to the operating environment.
- Its design requires very little fluid. If operated properly, Bear-Loc® does not leak. This also means environmental conditions such as heat will not adversely impact the fluid.
- We test and certify Bear-Loc® to perform to the customer’s load holding requirement. When the system is operated at, or even somewhat above its rated psi, it will not drop its load and can hold it as long as required.
- Risk prevention relevant to specific industries and applications. Bear-Loc® is known for its reliable performance where other options falter, such as extremely large load control capability, as well as high system stiffness (e.g. wind towers), zero backlash, and infinite position locking (enhancing performance in applications such as crash wall and other testing, and gates in hydro-control. The latter benefits with operating efficiencies and protection from debris strikes.) With infinite position and bi-directional locking, unplanned movement is impossible in ANY direction when operated within its rated capacity.
- The right design for the right system. Our engineering team works with you to assure that the Bear-Loc® works seamlessly with your system, whether new design or retrofit. Bear-Loc® is available as rod, piston, or rotary lock, available in both tie rod and mill type construction. A variety of mounting options, such as flange, foot, trunnion, heavy flange, and eye mount are also available.
More Preventative Tips
Hydraulic system issues are inevitable at some point. However, simple steps can help you avoid these issues and increase the longevity of your hydraulic system. On top of effective troubleshooting, you can prevent hydraulic system failure by taking the following steps.
- Follow specifications: We can trace the most common hydraulic system issues back to fundamental system problems like incompatible or improperly installed parts. For this reason, it is essential to always double-check specifications to ensure your purchased parts can work together seamlessly.
- Consult with professionals: When purchasing new equipment, consult with industry peers and professionals to discover what they recommend. While manufacturers can tell you how a product should work, industry professionals can provide concrete examples of how well the equipment works for their industry and/or applications.
- Perform maintenance: It is essential to focus your operations on equipment longevity. Review your daily, monthly, and annual maintenance procedures to ensure you are covering every aspect of your system according to best maintenance practices and catch symptoms early on.
York Precision offers in-house design, engineering expertise, and machining and manufacturing capabilities to produce a hydraulic locking device that meets your exact specifications. Why take a chance on performance and safety? Contact us today for a free quote.
Hydraulic System Maintenance
Regularly review hydraulic system maintenance, always following manufacturer recommendations and industry best practices. Also, consider the storage condition, external influences, working pressure, and usage frequency of your system to tailor your maintenance schedule and procedures.
Generally speaking, you should perform maintenance at three levels.
- Daily tasks: Take care of a few simple daily checks to avoid issues. For example, personnel should check the oil levels, check the lines and connections, and listen to the pump for abnormal sounds.
- Routine tasks: Plan and execute a weekly and monthly maintenance routine, checking for the most common failure sources given your system's working conditions. These should include components, filters, and the condition of the oil.
- Complete system checks: Depending on the conditions of your system, you and your team should perform complete systems checks monthly, quarterly, or annually. Tasks should include running a comprehensive report on the system, cleaning devices, draining the system, and replacing damaged parts.
How to Work Safely With Hydraulics
When completing system maintenance, it is essential to follow basic safety procedures. Faulty or broken parts can cause leaks, bursts, and projectiles that can severely injure personnel. Some common injuries include bruises, cuts, and abrasions. However, pinhole leaks can inject oil into the body, causing septicemia that can result in the loss of a limb if not addressed immediately. To avoid these injuries, be sure to follow basic safety guidelines.
- Wear safety equipment: Always wear appropriate safety gear when working close to a system, including a helmet, glasses, gloves, and protective clothing and shoes.
- Power down systems: Never service a running hydraulic system unless it is strictly necessary.
- Be mindful of location: Do not stand at endpoints while working on hydraulic systems. This safety measure can help prevent loss of limb and life, as there is a lot of pressure built up in these areas that can release and result in life-threatening situations.
- Use reliable, fail-safe, load-holding and locking equipment: As discussed, fail-safe load-holding saves lives.
- Use caution around running systems: Always keep an eye out on pressure taps, couplings, and lines when they are under pressure. If something does not look right, power down the system before checking it. Loose or faulty parts can easily become deadly projectiles.
The best safety measures, however, are to perform excellent maintenance and use high-quality parts. If you are looking for a quality hydraulic component manufacturer, York Precision Machining & Hydraulics can help.
While personnel can implement all the necessary safety measures when working with hydraulics, human error is bound to happen in some cases. The Bear-Loc® hydraulic locking system is in use globally and offers an unparalleled solution. The system does not require operator intervention, which further prevents injury and damage; and it can operate in environments where humans cannot.
The Importance of Load-Holding and Locking Devices in Hydraulic Systems
Load-holding valves are critical safety devices used to hold a hydraulic system-applied load in place and prevent unintended motion. When operating effectively, these devices can enhance the safety and control of a hydraulic circuit. However, when any failure occurs with the valves or other components in the hydraulic system, the load can move or drop if the load-holding device is the only measure of safety. For this reason, if an application requires valves, they are most effective when used in conjunction with a fail-safe locking device
Bear-Loc® can provide the necessary safety support when valves malfunction or any other component disrupts load stability. This device locks instantly, ensuring the load holds, even if other components are compromised, preventing accidents or hazards.
Here are some additional reasons why Bear-Loc’s® fail-safe load-control is vital for hydraulic system operation and safety:
Better Load Stability and Control
- Holds load in a specific position for as long as required without drifting.
- Helps maintain control when the load is lowered.
- The Bear-Loc® assures ultimate load stability during critical operations.
Enhanced Safety Measures
- Plays a critical role in protecting personnel and equipment.
- Automatically locks when pressure is lost.
Increased Load Capacity
The patented design of the Bear-Loc® can handle many higher-demand applications. The durable locking device can be customized to hold up to 4 million pounds with an operation pressure that ranges up to 5,000 pounds per square inch (psi) and up to 27 inches in rod diameter. These factors contribute to superior load capacity.
Choose York PMH for Hydraulics Help
At York Precision Machining & Hydraulics, we highly value safety and know many of our clients are interested in the topic of hydraulic systems failure. People want to know how hydraulic systems fail, which is why we wanted to share this information with you. If you're interested in learning more about fluid power components and systems, you can trust us to help.
York Precision Machining & Hydraulics is an industry leader in precision fluid power components and systems. We are a top components manufacturer for aerospace, defense, commercial and industrial businesses worldwide, operating out of a state-of-the-art 65,000-square-foot facility in York, PA. With nearly 50 years of industry experience, we set the standard for hydraulic fluid power components. If you need hydraulic equipment, York PMH is fully equipped to handle your project from design to assembly.
Contact York Precision Machining & Hydraulics today for all your hydraulic needs.
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