Hydraulic Pump Failure

Hydraulic pump system problems can stop operations, causing delays and profit losses. Recognizing signs of failing pumps before they quit working could prevent productivity loss. Even if a system does fail, managers who know hydraulic pump troubleshooting basics could address minor issues immediately without needing to call a professional. Diagnosing the problem will help your business save money by knowing when a pump requires professional service.

How Do You Know If Your Hydraulic Pump Is Bad?

Before getting into the reasons hydraulic pumps break, it’s essential to know the signs that your hydraulic pump is broken or in danger of breaking. Some of these signs include:

Noisy system: All mechanical systems make some noise, and hydraulic systems are no exception. But if you are hearing very loud banging or knocking, there’s a good chance that your pump is experiencing aeration or cavitation, which could lead to pump failure.
High temperature: If your hydraulic system is exceeding the recommended temperature level of 82 degrees Celsius, this could be due to a buildup of debris in the filters preventing the system from dissipating heat. This problem is one you will want to address quickly, as high heat can damage your system.
Slow system: If your system isn’t operating as quickly as it’s supposed to, you have a problem. A slow hydraulic system means a loss of flow, which typically means internal leakage.

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What Causes Hydraulic Pump Failure?

Before hydraulic pumps can receive service, a technician needs to determine the cause of failure. Understanding these causes will help your company integrate methods to avoid breakdowns. Additionally, the various causes of failure often cause different symptoms in the hydraulic pump.

Most cases of pump failure result from the following conditions.

1. Fluid Contamination

Keeping hydraulic fluid clean is vital to the safe operation of the system. Contamination in the liquid from dirt, oil or water can cause damage to the parts of the system the fluid contacts. Hydraulic systems require precision between moving parts, allowing them to run smoothly without significant gaps that could leak fluid. Dirt in the hydraulic fluid can deposit itself onto the surfaces of these moving parts, causing them to stick or wear down.

If contamination damaged the components of the system, even changing the fluid will not help restore operations. The entire system requires thorough cleaning and replacement of any damaged parts before adding new oil to it. Because it can occur so quickly and cause such extensive damage, fluid contamination is one of the most common causes of pump failure. It also requires the most thorough inspection, cleaning and replacement of parts after it happens to restore the pump’s operation.

2. Aeration

Contamination takes many forms, including air in the hydraulic fluid. While this does not cause the same type of damage as dirt in the system, aeration has a litany of issues it produces on its own. The hydraulic system must remain sealed for proper pressure to build up. When air gets into the pump, the pressure of the fluid increases to dangerous levels. Any lodged debris can break off and enter the fluid.

Additionally, the extra pressure can cause implosions and higher temperatures. When air enters the system, repairing the pump promptly can avoid more severe damage to the system that might require replacement of the entire hydraulic pump. Signs of aeration include an erratic, high-pitched whine and foamy hydraulic fluid.

3. Cavitation

Pressure inside a hydraulic pump allows the system to function, but when the fluid does not fully take up all the available space, the system cannot build up proper pressure. Instead, air gets into the hydraulic oil, causing excessive heat and improper pressure. Cavitation refers to the cavities of air outside the hydraulic fluid, compared to aeration from the air inside the liquid.

Causes of cavitation include intake lines that are too long, pumps operating too fast or fluid that has too high a viscosity. Contamination of the suction strainer is the most common reason for cavitation, though, because this problem often gets neglected for too long because the strainer is hard to reach. Issues from cavitation resemble those caused by aeration, but unlike the erratic whining of aeration, cavitation often causes a consistent high-pitched whine that repeats every 20 to 30 seconds.

4. Excessive Heat

Overheating of hydraulic fluid degrades the oil rapidly and ruins the entire system from the inside. Components, seals and hoses all wear out faster from too much heat. While the exact temperatures depend on the type of hydraulic fluid used and the system, anytime oil runs through the system over 82 degrees Celsius (180 degrees Fahrenheit), damage can occur. Because every part of a hydraulic system generates heat, the fluid will naturally increase in temperature during operation. Too much heat damages the system.

While excessive heat causes problems, it also tends to be a symptom of other issues with the hydraulic system. Aeration, fluid contamination and cavitation may all contribute to overheating. However, if everything in the pump checks out, the hydraulic pump may not dissipate heat properly. To solve this, add an oil cooler to the system. Despite the aversion many have to adding oil coolers to hydraulic systems, a cooler can maintain a safe operating temperature for the fluid to prevent heat damage. Additionally, increasing the fluid tank volume will not keep the temperature in a safe range.

5. Overpressurization

While hydraulic pumps operate under pressure, excessive pressure will result in premature wear on the system. With overpressurization, the system will not lubricate properly, valve plates can separate, and the machinery will sustain damage. Faulty pressure-relief components often cause overpressurization. However, a poorly designed pump can allow drain lines to connect to the return filter instead of passing through dedicated lines. Regularly monitoring and adjusting pressure with correctly adjusted relief valves can prevent too much pressure from building in the system.

6. Poor Hydraulic Fluid Viscosity

Not all hydraulic systems use the same fluid viscosity. Several factors determine the correct viscosity for an operation. If the fluid viscosity is too low, components of the hydraulic system can experience friction and subsequent overworking of the pump. When the fluid’s viscosity is too high, it makes the pump inefficient and increasing the chance of cavitation.

Temperature and viscosity are closely related. While some erroneously believe lower viscosity fluids allow for lower operating temperatures, they actually increase the temperature from higher friction. High viscosity fluids can enable the system to work with a lower temperature, which increases the life of the equipment. The appropriate operating temperatures depend on the viscosity index of the oil, which maintains the fluid’s texture within a given temperature range.

Higher viscosity indices indicate fluids that do not thin excessively in high temperatures or thicken too much when used in low temperatures. Generally, machinery used in cold ambient temperatures will need hydraulic fluid with a high viscosity index to prevent moving too slowly as the surrounding air cools. Maintaining the correct temperature range for the fluid’s viscosity will prevent the wear on the components from low viscosity and the cavitation caused by high viscosity.

7. Implosion

Implosion means something is blowing in on itself. This action occurs when the air bubbles in hydraulic fluid collapse under pressure. The resulting implosion makes a loud noise in the pump. In addition to the disturbing sound of the implosions, the tiny bubbles bursting create repeated micro damages to the interior of the system, which will wear down the interior of the metal in a process called inertial cavitation. Preventing cavitation can keep implosions from happening.

8. Pump Aeration

Just as air in the system creates problems, the air in the pump is just as bad. Worn pump seals can admit air into the system, causing aeration. Those nearby may hear the hydraulic pump making a whining noise during operation when either aeration or cavitation happens. Over time, the aerated fluid will increase in temperature, resulting in further damage to the seals, which will allow more air in. Finding the air leak and fixing it before replacing the fluid can help stop aeration.

How to Avoid Hydraulic System Failure

While hydraulic system failure can occur for a range of reasons, floor managers and maintenance personnel have several methods at hand to prevent problems. Regular maintenance can also identify issues before irreparable damage occurs. Three maintenance tasks have the most significant effect on hydraulic system efficiency and longevity:

Maintaining fluid levels
Keeping the system clean
Checking connections

Other tasks augment these to increase the health of the overall system and help reduce the chances of abrupt failure.

1. Keep the System Clean

Monitor the cleanliness of the hydraulic fluid and its levels regularly. If the fluid appears shiny, suspect oil contamination. Foamy means air has entered the system. Should you see dirt, particulate matter has gotten into the fluid, indicating a possible breakdown of components somewhere inside or a clogged filter. Send the hydraulic pump for service to have it pulled apart, inspected, cleaned, restored and refilled with fresh fluid.

2. Filter Hydraulic Oil Correctly

Proper filtration requires regularly changing the filters when they become dirty, not on a specific schedule. Changing the filters too soon will waste money on new parts. However, waiting until after the bypass valve opens puts a strain on the system and increases the chances of dirt getting into the fluid. To correctly time filter changes, continuously monitor the filter for a pressure drop.

Where you have filters installed on the hydraulic pump also makes a difference. If you include too many filters, the system must work harder to draw the fluid through it. In fact, the restricted intake from clogged or excessive numbers of filters can reduce the gear pump’s life by 56 percent. Avoid having filters on the pump inlet — the fluid in the reservoir the pump inlet draws from should already be clean, so don’t restrict its flow with a screen. Similarly, don’t place a filter over the drain lines for piston motors and pumps. The filters do more harm by slowing flow than good in keeping the system clean.

3. Keep Components Cool

Monitor the temperatures of the system to ensure it does not run too hot. An oil cooler could help keep the temperatures at safe levels in hot climates or for systems that run hot. Keeping the hydraulic fluid at its recommended operating temperature range based on the oil’s velocity will prevent wear on the seals and hoses of the system.

4. Perform Visual Tests

Regularly inspect the hydraulic system for signs of wear, cracks, leaks or improper values on monitoring gauges. A visual inspection can spot the signs of many hydraulic system problems, and solutions become easier to reach when you know the issue. Check the electric motor and the pump shaft for proper running. Also, look carefully at the hydraulic fluid and its level. Keep the oil in the reservoir three inches above the suction. This depth prevents debris from getting sucked into the system by allowing enough room for it to sink to the bottom. Also, this amount of oil prevents vortices from forming in the reservoir, which can cause aeration.

5. Perform Sound Checks

Sound checks play an important role in determining if a problem exists. Both aeration and cavitation notoriously cause the pump to make whining noises. Sometimes, aeration may cause a knocking sound as implosions occur from bursting bubbles of air in the hydraulic fluid. Any unusual sounds should prompt a more thorough inspection of the system.

What to Do If Your Hydraulic Pump Fails

Even with perfect maintenance, eventually, failure will happen to a hydraulic pump. When this occurs, first troubleshoot and perform tests to see if the problem is minor enough for in-house servicing. However, if the problem is beyond your company’s maintenance personnel to repair, send it to us at Global Electronic Service for service.

Troubleshoot: First, troubleshoot the system to try to determine the cause. Look at the oil level and the quality of the hydraulic fluid. If the fluid appears contaminated or is too low, correct it. Check for leaks if the hydraulic pump is not building pressure. Examine the quality of pressure release valves if the pressure runs too high. Conducting maintenance tasks can often help to spot problems and give clues to their possible causes.
Perform tests: Performing tests of the temperature, flow rate, pressure and more gives data necessary to determine the problem and its degree of severity.
Send it for repair: If basic solutions do not work to correct the issues, or if troubleshooting cannot determine the cause, send the pump to us at Global Electronic Services. Our trained and certified technicians will follow a thorough process for finding the cause of the problem and making all necessary repairs before sending it back. With rush delivery, your business could get its pump back in as little as one to two days, reducing downtime and production delays.

Contact Global Electronic Services for Hydraulic Repair

Global Electronic Services has factory-trained, certified technicians who are well-versed in hydraulic systems and hydraulic problems and solutions. If you’re delaying repairing your hydraulics because you’re afraid of taking them offline, you should know that Global Electronic Services can complete your repair in a matter of days. For more information, call 877-249-1701 or contact Global Electronic Services online.