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We recently helped out one of our clients with a hydraulic issue he was having. He wrote to us and stated that he had a hydraulic system that was running perfectly fine when it was running on a horizontal level. But as soon as it was running at any measure of vertical angle, everything went to pot. It would jerk and become very noisy in operation. He told us that he suspected it could be to do with the pump, and that it would be such a pain if it was as that was a particularly hard pump to reach and to dismantle.
Think for a moment on his challenge. Using the information that you have, what do you think the issue could be?
Just as with every troubleshooting challenge, there is some information that has been provided to run off. Some of it will clearly be fact, and some of it could be categorised as opinion. Some may even be considered fiction. How you use this information and process it will result in the next turn that you next take. Whether you have taken the correct turn to start with will depend on what you made of the information that you were provided with. To get an accurate diagnosis rapidly, this is very important.
So let’s work through a process of troubleshooting. What can we ascertain from the information that we have? After considering the information that we have, it looks like it isn’t a typical hydraulic issue, and that we should try to find the probable reasons for its behaviour to make troubleshooting easier. There aren’t a lot to choose from.
I write to the customer asking him to check the mechanical parts of the machine, after all these are easier to reach than digging into the machine to get to the pump. The guy writes back after a day or so and tells me that the drive chain was at fault and it had been worn down considerably. On the horizontal level, it would still operate, but when it was at an angle the worn nubbins would let go of the chain and it was this that was causing the jerking.
This is why it’s important to not take any false turns with troubleshooting. After all, he could have started working on getting the pump out – only to discover his worn chain later on down. As it was, he saved himself a costly and time consuming wrong turn.
Made of a number of precision machined components, hydraulic equipment and systems require care and maintenance to get the best of them and in order to give them what they need for long lasting and trouble-free operation.
We’ve covered troubleshooting before, and if you want to know more in further detail then check out our blog posts on:
Troubleshoot Hydraulics: Basic Knowledge
Troubleshooting Hydraulic Relief Valves
This checklist is for those who have not had extensive experience with troubleshooting hydraulics and it might suit your interns or newbies in the workshop.
Let’s get started.
First off, it’s essential to keep all of the hydraulic system clean. This includes the hydraulic fluid. Oil and oil filters need to be changed at regular intervals. You could say that dirt and grime is your and your equipment’s worst enemy and it’s your role to keep it at bay and prevent it from messing up your machinery and its peripherals.
Here is a checklist of what is at the root of most trouble:
1. The fluid or oil being used is not of the correct viscosity.
2. There is not enough fluid or oil in the system
3. There is a leak
4. There is dirt, moisture or there is another foreign body in the system
5. There is air in the system
6. Structural failure.
7. Adjustments have been made but they are wrong
Here are some shortcuts to answers that you can refer to when getting started with hydraulic troubleshooting:
Your Pump is Operating Incorrectly and not delivering fluid or oil. It could be down to any of these reasons:
· The fluid is too low in the reservoir. You may need to check its level and refill if necessary.
· If there is a hole in your intake pipe allowing air to pass through, you may hear a noise or experience erratic results. This will need to be repaired. Alternatively there could be a blockage in your filter. In which case, you will need to clean it.
· The oil is too thick and the viscosity is too heavy. Check the specs suggested by the manufacturer.
· The pump shaft is rotating in the wrong direction. Reverse it otherwise you will cause irreparable damage as there won’t be enough lubricant.
· Dirt in the pump – clean it.
Your System is Not Developing Pressure
The most likely causes for this type of situation are:
· The pump is not delivering fluid (see info above – with remedies listed)
· The relief valve is malfunctioning either through leakage, incorrect settings or because the valve spring is broken. You may need to check the settings according to the manufacturer, check the valve seat to look for either dirt or scoring or even replace the spring and then adjust it as suitable.
· The valves may be allowing the oil to be recirculated through the system. Check the directional valve to ascertain what the situation is with it.
· There is leakage internally in the valves or the cylinders. Check these components and their condition.
Pump is making noise
· The intake line or the filter is not allowing fluid to pass. Clean these and assure there are no kinks or anything to stop them being fully open.
· There are air leaks either in the intake pipe at the joints, at the pump shaft packing or through the inlet pipe opening. You can check the joints for leaks by pouring on oil. Also check the shaft by pouring oil onto it and check that the inlet pipes are below the oil level in the reservoir to ensure that suction is strong enough.
· If you are seeing air bubbles, you may need to use an oil with a foam depressant.
· Check the reservoir air vent to see if it’s plugged, if so clean it.
· You may find that the pump is running too fast, in which case you will need to refer to the manufacturer’s specifications.
· The oil is at the wrong viscosity. Again, check the manufacturer’s specifications for details.
· Check whether the filter is of the correct size, as this could also be a problem. Refer to manufacturer’s specs for details.
· Check for work or broken components and parts, and replace as necessary.
If you’re experiencing an external oil leak around the pump, you may need to look for:
· Worn shaft packing which needs replacing
· Head packing damaged, again replace it.
· Loose or broken parts, which may need to be tightened or replaced.
Excessive wear can be caused by and remedied as follows:
· Abrasive material or dirt in oil being circulated. Clean and/or replace the filter and change the oil.
· If the viscosity of the oil is too low, check what is recommended by the manufacturers.
· Pressure could be too high for maximum rating of the pump. In which case you may need to check the settings of the relief valve or regulator valve.
· The drive is not aligned correctly. Check this and correct as appropriately.
· Air is in the system. This will need to be removed.
Broken pump parts can come about from:
· Pressures are above the maximum pump rating check the relief or regulator valve settings.
· Seizure from lack of oil in the system. Check the level of the reservoir, the oil filter and the suction line.
· Dirt or material in the pump – clean it and check the filter.
· The head is screwed on too tight – check the specifications as listed by the manufacturer.
Follow our blog for more handy hydraulic system troubleshooting checklists.
Electrostatic charge builds when there are two bodies moving and creating friction. The fact is that this also occurs in hydraulic systems from the friction caused by system components with moving fluid.
Although we haven’t had a lot of situations that have involved electrostatic discharge, it is still something that every engineer should be aware of.
When an electrostatic discharge occurs, there is a clicking noise as charge increases and is then released. This is something that will often occur in a filter – leaving burn marks and potentially other damage.
With the increasing preference of using non-metallic additives in hydraulic oils the electrostatic charge could be on the increase. Those hydraulic oils that contain anti-wear additives that are zinc-based have considerably high conductivity.
Conductivity in hydraulic oils helps when it comes to moving electrostatic charge around the system. Although zinc-based additives will rarely collect enough charge to cause a big problem, synthetic oils can. This is because they have less conductivity and therefore will potentially accumulate more charge before discharging it.
Another change that could lead to an increase in electrostatic discharge is that there has been a change made to the materials that filter elements are made of. In order to make them easier to dispose of them in an eco-friendly way, they have more non-metallic material in the design, which lowers conductivity and therefore increases the capacitance.
The manufacturers of hydraulic filters are aware of these issues, and are looking into how they can minimise or even eliminate these issues.
However, if you come across a situation where there is electrostatic discharge in the meantime, then consider this:
By adding larger filter elements you can reduce flow density and therefore the amount of charge that is being generated. You might also want to consider increasing the tank size so that the time between charge generations increases.
This is one of the reasons why you shouldn’t skimp on tank size or on filter capacity.
Hydraulics has been around for a very long time. But are you aware of how far it has actually come? You wouldn’t be alone if you responded with no. It is a very technical subject that can be quite difficult to understand, but in this article we want to tell you the story of hydraulics! We want to share with you who discovered hydraulics, what it was originally used for and how hydraulic power got to where it is today.
So why don’t we start at the beginning! Where does the word hydraulic come from?
The word hydraulic originates from the Greek word ‘Hydros’ which means water. Why water? Well, this is because water was the first liquid to be used in the hydraulic system. Today, hydraulics includes the physical behaviour of all liquids, not just water.
If you’ve been in the hydraulic industry for some time, there’s no doubt that at some point you will have seen cloudy oil. This is what happens when there is contamination with water above the oil’s level of saturation. The definition of a saturation level is how much water can dissolve in oil – for mineral hydraulic oil this will typically be around the 200 to 300 ppm at 68 F or 20 C.
As an aside, something worth knowing is that bearing life can be increased by almost 150% if water concentration is reduced to just 25 ppm.
The more water in the oil, the more issues you’re going to face. One of our engineers recently witnessed oil that so was incredibly cloudy because it had over 10,000 ppm of water in it which actually made it more than 1% water!
Here’s what happens when there is water in hydraulic fluid:
· Either depletes or reacts with additives to form by-products that can corrode some metals
· Clogs filters by reducing filterability
· Increases ability of air entrainment
· The likelihood of cavitation increases
· Lubricating film-strength is reduced leading to corrosion and wear vulnerability
It’s also possible to spawn bacteria with water present in oil.
Measuring and Removing Water
How can you measure how much oil and how much water you have in your hydraulic fluid?
The test that is considered to be the standard laboratory method is the Karl Fischer Volumetric Regent Method which others may know simply as the Karl Fischer test. Another method sometimes used is the FTIR or Fourier transform infrared spectroscopy test. However, this is a test that can only really be considered effective with oil and water mixes that are greater than 1000 ppm of water. If you’re serious about measuring water contamination, we recommend that you go with the Karl Fischer.
Now that you know that there are some very unpleasant side effects when there is water in your oil, what are you options with regards to removing it? If you’ve got a system that has only a small volume of oil, then you may opt to change the oil. This option will most likely prove to be the most cost effective approach. For larger oil volumes, it’s best to use filters built for water removal when there is small amounts of water involved.
Water removal filters come in two types, polymeric and coalescing. The former works by using chemicals that attract water. They absorb water drops and retain them permanently. Whereas coalescing filters collect the water and put it into a collector which is drained once in a while. Water that has been dissolved will not be collected by either filter types.
Another approach to collect water is the headspace dehumidification approach. This uses the reservoir’s headspace to circulate and dehumidify the air. Water will then migrate to the headspace where it is removed by a dehumidifier.
Headspace flush is another approach that is similar to the previous method, except that it is collected by a small flow of dry compressed air that is flushed through the headspace. The dry air will pick up the water.
One more approach is to use a variation on the headspace flush by using a hygroscopic breather and then connecting a vacuum pump. This approach is reliant on a spare port located on the top of the reservoir, as distant from the breather as possible. This method does not need a source of dry compressed air.
We are in the business of supplying mobile power packs for hydraulic systems. If you want to know more about our products, browse through our hydraulic unit product pages or call us for a no obligation chat.
It’s not an easy job to troubleshoot a hydraulic system. It something that always involves time, and in some cases even some creativity. Incorrectly diagnosing any issues can prolong downtime and may even result in unnecessary expense from replacing components that may still be working fine or at worst are serviceable. It’s important to take an organised and logical approach to avoid this happening.
Prior to hiring a specialist engineer, take the time to investigate the problem yourself and eliminate any obvious causes. Great expense can be wasted on calling in an engineer too soon when the issue is as simple as something like a loose wire or a pin that has fallen out.
Although your called-in engineer won’t mind finding something small and obvious as being the root cause of your issue. Of course, he will still be paid for the call out on an hourly basis, but you will definitely mind. You will be annoyed with yourself for not having discovered something so obvious that has now cost you needless expense.
Paying out for something that you didn’t actually need is not pleasurable. However, it’s not as bad as having to pay out to replace a component that has nothing wrong with it or could be serviced instead of having discarded it.
Not being knowledgeable about your system can leave you potentially exposed to being unintentionally ‘hoodwinked’ by an engineer too. In some cases, they may not know their subject matter much better than you do, and they may go so far as to recommend the replacement of parts when that’s not what the matter is.
In some cases, it’s wise to seek a second opinion, especially if the repairs are likely to be of great cost.
Although hydraulic systems must be lauded for the amazing technological innovation that it is, there are also some other points that you need to know.
When it comes to cars, there are a variety of ways that hydraulics brought benefits from their invention and use. For example, if you have a flat tyre you will reach for the jack to lift up your car to change the tyre. In more modern times the hand cranked device has evolved into the hydraulic jack. Not only does it save your own energy to use these devices, but it will also save time. (FYI here at HydraProducts we have experience in the automotive industry and design hydraulic drive shafts for Mondeo cars).
Another car related hydraulic use is that of hydraulic brakes. The power of the hydraulic system means that there is considerably greater stopping power than that delivered through other braking methods. Car designers are increasingly making use of hydraulics when it comes to back doors and closers. Doors on large vehicles used to difficult to open and close, but with an automatic closer vehicle owners that have their hands full of shopping or other items can conveniently operate this feature for easy access and use of their boot.
It’s not only with cars that hydraulics have entered into all areas of our lives. There are also other tools such as pulleys and levers.
However, for the lay person there are also some risks. For example, hydraulics can easily crush fingers and hands due to their power. A child’s hand in the wrong place at the wrong time can be hurt if a hydraulic powered door were to close on it.
It’s also important to know that the fluid in hydraulic systems can also be made up of very dangerous chemicals. They can cause burns if they touch human skin, although not every substance is harmful, it’s wise to pay attention to leaks and potential leaks.
Hydraulic systems that are not carefully designed and manufactured can cause injury if not handled safely.
All our designs take safety into mind as much as possible. We also make bespoke hydraulic systems for applications that can benefit from hydraulic power.
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