Local time: Fri 12 Jun 2020 05:40

Blog

 

Hydraulic Pump Troubleshooting Tips

From the oil refining sector to the automotive field, a lot of industries have come to rely on hydraulic systems for certain critical functions. Hydraulic systems—and the hydraulic pumps that serve as vital components within them—can be arranged in a varied range of forms. What these systems generally share in common, however, is a tendency to experience a decline in functionality over time. Below we will discuss hydraulic pump troubleshooting on a case by case basis, so you can maintain the function of your hydraulic system.

Common Hydraulic Problems

Troubleshooting is just a fact of life for mechanical systems that consist of a variety of parts and components that must operate at peak efficiency for extended periods. No matter how well designed the system may be, problems will eventually develop. The system may gradually lose pressure, become overheated, or even experience a catastrophic failure that makes everything suddenly stop dead. When this occurs, the operator is left with the unenviable task of figuring out exactly what went wrong and how to fix it.

Most commonly, operating failure or inefficiency in a hydraulic system can be traced to one or more pumps that aren’t functioning correctly. It’s not difficult to understand why—pumps consist of a number of moving parts that come into contact with abrasive contaminants in the oil. If only one pump part isn’t working right, it can create a ripple effect that leads to system-wide issues and, ultimately, hydraulic system failure.

Troubleshooting Tips for Hydraulic Pumps

What follows is intended as an overview of the troubleshooting process for hydraulic pumps—how to identify problems and how to correct them. It is not a comprehensive guide to fixing pumps, but it should provide operators with some useful and effective hydraulic troubleshooting tips for tracing issues to their precise source. So, let’s get started.

General Hydraulic Pumps

First, we’ll explore issues that tend to occur in the general range of hydraulic pumps.

Pump cavitation – This common phenomenon refers to the incapacity of the pump to transport hydraulic fluid properly due to damage caused by the implosion of air bubbles in the fluid. Pumps suffering from cavitation tend to become noisy; they may also begin to overheat and lose pressure. This can easily shorten the lifespan of the pump if the problem continues unchecked.

When cavitation happens, you should check the suction strainer, which may be either fully or partially blocked. Be advised that, in some cases, the strainer will be submerged in the oil reservoir, so be sure to check here if it isn’t visible. Give the strainer a thorough cleaning before you reinstall it—compressed air will generally be appropriate for this purpose.

While you have the strainer in your hands, it’s also a good idea to make sure that it is the proper size—sometimes it’s too small, and that could be the ultimate cause of your cavitation issues.

Check the oil viscosity. Forcing a hydraulic pump to move higher viscosity oil than it is designed for may lead to cavitation.

Examine the inlet hoses. These sometimes collapse, either completely or when subjected to a vacuum, and therefore become incapable of conveying oil correctly. Hoses with internal wire reinforcement are recommended to prevent this development.

Water in the system – If water is leaking into your hydraulic system, it tends to reveal itself in the form of milky-looking or cloudy oil.

In some cases, the culprit is condensation forming on the inside of the reservoir. You can fix this by carefully letting water out through the reservoir’s drain valve.

Also, examine the shell and tube heat exchanger, if used, for potential leaks.

Excessive noise – Again, this can be caused by cavitation, but there may be other factors, including aeration, that play into this, and these need to be taken into consideration as well. Check for loose connections and couplings.

Another potential cause is a pump running faster than its design allows. Excessive oil viscosity can cause this issue as well.

Oil leaks – Oil leakage that occurs in the pump area may be caused by very hot or very abrasive fluids that damage the shaft seals. Incorrect pump rotation or excessive inlet pressure in gear pumps or excessive case pressures in piston pumps can lead to shaft seal leaks as well.

In addition, check to ensure that the system operating pressure isn’t too high.

Overheated oil – Excessively hot oil may lead to all sorts of issues with your hydraulic system and your pumps. You may need to fit a cooler or increase the size of the reservoir to eliminate this problem. This is another issue that may be triggered by excessive oil viscosity, so check that also.

Dirty oil – Hydraulic circuits should always be fitted with suitable filters. The simplest system is to always make certain that the oil in the reservoir is clean by fully filtering the return oil through a very fine glass fibre return filter and changing the filter element on a regular basis before it begins to bypass. Contaminated / dirty oil is the number one cause of hydraulic pump failure.

Vane Pumps

The vane pump is characterised by a rotating shaft that drives a ring of sliding vanes. These vanes create chambers of continually adjusting size that convey fluid to their destination.

Vane pumps can encounter difficulties for a variety of reasons, including many that we have listed in the space above, but a lot of problems with these pumps are linked to dirty, contaminated hydraulic fluids. Contamination can occur in a number of ways.

Sometimes a rebuilt hydraulic system contains old fluids that were never properly flushed out. In other cases, contamination is introduced into the system from the surrounding environment. Another cause is tiny particulate matter produced through component wear that circulates in the hydraulic fluid.

Tiny abrasive particles in a stream of oil can cause major damage over time, by wearing away at components that haven’t been designed to tolerate contact with such matter. Eventually, total pump failure will result.

If you work with vane pumps, you will need to be particularly cautious about keeping your hydraulic fluid clean. Try to make sure contamination and other foreign particulate matter have no means of entry into your hydraulic system. It’s a good idea to purge old fluid at periodic intervals, replace it with brand-new fluid, and fit fully effective filters made from glass fibre rather than paper. If you’re not certain of the age of the hydraulic fluid—this may happen if you are assuming maintenance responsibilities for a system that had previously been managed by others—it may be wise to perform a flush and replace to be safe.

It is important to bear in mind, however, that you could easily introduce particulate matter into your hydraulic system during the cleaning process. This is because the immediate surroundings where your system resides may be contaminated by dust and other fine airborne particles. You can minimise this possibility of damage and hydraulic system failure by thoroughly cleaning the area prior to opening the system up.

Piston Pumps

Piston pumps feature pistons in cylinders whose motions transport fluid through a hydraulic system. Here are a few maintenance considerations to bear in mind if you have to manage these types of pumps:

With piston pumps, it's important to ensure that the pressure compensator, if one is present, remains configured at a cut-off pressure setting lower than the setting of the circuit relief valve. If this condition is not met, then the compensator will fail to perform its function correctly—with potentially serious consequences.

Improper fluid pressure can pose a major problem, and you can check for this by setting up a pressure gauge to measure the pressure of the fluid in the system. If there's no pressure, check to see whether the shaft is rotating. If it isn’t rotating, you’ve probably found the problem; if it is, you still need to check that it’s turning in the right direction—incorrect rotation is common. In cases where the pressure is normal, you need to check the pump compensator and relief valve to make sure they are working correctly.

Understand the Fundamental Laws of Hydraulics

When operating any pump, it’s important to understand how hydraulics work in order to uncover potential issues. For example, if there isn’t enough pressure, there is leakage either within the pump or elsewhere in the system. This is because the hydraulic pump does not produce pressure. it produces flow, and the resistance to this is what generates the pressure. Therefore, if the pump isn’t producing flow, it may not be getting enough oil, which may be due to low reservoir levels; a clogged breather, filter, or suction strainer; or a defective pump inlet pipe, gauze or valve if fitted.

Pump flow may also be escaping from the circuit. This may indicate a leak, but you need a schematic diagram of the system to identify all potential points of escape. As fluid under pressure will find the point of least resistance, you must use a keen eye to pinpoint any possible trouble spot and perform effective hydraulic troubleshooting.

Heat is another cause for concern. A hydraulic system will generate heat whenever there is a pressure drop, which, in turn, can indicate internal leakage. To apply this law to hydraulic pump troubleshooting, you want to quickly find where the hottest components are. You can use an infrared thermometer to find likely points of internal leakage. If the system is functioning properly, the hottest part is likely to be the pump case.

Troubleshoot Your Hydraulic Pumps with the Help of White House Products Ltd.

Diagnosing hydraulic pump issues can be difficult, and there is more to the matter than we have covered in this limited space. If you are experiencing problems with your pumps, we invite you to contact the team at White House Products Ltd. For help with hydraulic system issues, call +44 (0)1475 742500 or submit your enquiry and details online.

back to blog posts