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Spring is finally here - in its full beautiful entirety with sunshine and plenty of tabloid coverage telling us that it’s going to be hotter than Ibiza. All part of the glorious British summertime!
This week we’ve got five tips for you on giving your hydraulic equipment a spring maintenance session.
Take stock – As the old Chinese saying goes, ‘He who fails to prepare, prepares to fail’. That’s definitely something to consider when it comes to hydraulic systems. It’s an often forgotten task to prepare for failures by ordering spare parts upfront so that they’re on hand for a speedy change out.
It’s a recommend practice to keep your paperwork up to date of what you’ve purchased on each machine so that you can cross reference your parts including valves, pumps and cylinders with inventory to ensure that you have what you need on hand and ready to use.
You’ll no doubt already be aware of the lead times on some parts. It’s a smart move to stock the parts you may need that are critical to operation. By revisiting what’s required for each machine, you can either opt to order parts or you can remove what you don’t need from the list.
Revise your schematics. Nobody can troubleshoot successfully with an out of date schematic, in particular if your machine is particularly large or of a complex design. Drawings need to be accurate and in line with the current inventory.
Oftentimes machines are upgraded or modified to be in line with safety regulations and overall safety considerations. If the schematic wasn’t revised to show the new layout of a machine, then engineers and technicians can waste time trying to fix a circuit they have no idea about. Although it’s best practice to change schematics at the time of the change, confirming that this has been done is a smart proactive move.
Check out your fluid. It’s important to investigate the condition of your fluid at least 4 times a year, and spring should be one of those times. Take a sample of your active fluid in to a clean sample bottle, so that you’re able to judge what true condition it’s in. Ideally your sample will be from the centre of a reservoir or from a return line so that you can get a fair representation of the fluid moving around the hydraulic equipment circuit.
You can measure what the particle count is in addition to the water contamination levels. You can also check the additive content and how long the oil is likely to be able to stay in service, thus potentially preventing needless maintenance.
Unless you know exactly what you’re looking for. Use a graph with your baseline so that you can see if there’s a big change from typical conditions. You should then have enough time to identify any issues and fix them before a major breakdown occurs.
Change filters. If you don’t have an electronic or other indicator to warn when the filter is full, you will need to schedule in regular checks. Spring is a good time to put this into practice. In an ideal world you will have a sign that the filter is clogged, emanating either from a light, a pop-up or a switch.
Although it’s great to schedule in filter changes, the only true way of knowing if one needs a change is by manually and visually checking whether it’s clogged. You will also need to look at the component wear whilst you’re there.
Spring clean. This is the actual spring clean itself. Of course, getting a very clean machine is every engineer’s dream. In reality hydraulic equipment attracts an incredible amount of dirt!
Although it’s fine to have dirt on the outside of your machine, having it on the inside is another matter entirely. It’s smart to ensure that the grime from the outside cannot reach the inside. Keep entry points closed and reduce the chances of contamination to keep your machine operating happily.
Are you interested in what can cut costs when it comes to Hydraulic Power in your business?
We can only imagine that the answer is ‘yes’ as most of us are. Well, we’ve got some good news for you. Today, we’re going to look at what the most common reasons are that hydraulic components fail, even those that have not been in service for long.
These points are worth making a note of:
1. Oil changes. It’s not necessary to keep changing the oil unless you have one of thes2 following conditions occurring.
The oil has degraded so far that the original additives have changed its makeup. Changing oil just because you feel it’s about time it’s changed is going to cost you a lot of outlay as oil is expensive. The larger your reservoir, the worse off you’ll be. However, if you keep operating your system with degraded oil, then that could cost you even more. Even changing the oil based on how long it’s been in service isn’t going to help. Oil needs to be analysed to fully understand its condition.
If you discover that your oil is contaminated with particles, the more economical manner to deal with this is to remove the particles through filtration.
So in summary, only change the oil when the additives have been depleted and the base oil is useless. You will have to perform oil analysis to make your decision.
2. Filter changes. It’s the same story with hydraulic filters. Changing them based on hours in service could mean that you’re too early or even too late. Early brings about waste as their capacity is not reached and you’ll be throwing away an unused amount of filter time. Changing them late is also an error as the particles will not be removed from the oil and therefore, it could lower the lifespan of each component in the entire hydraulic system.
The most effective approach is to only change filters once they have become full of dirt, but prior to the bypass valve opening. This may require a mechanism to be added that will monitor the pressure and deliver an alert when a point is reached. A clogging indicator is one of the most basic methods of handling this. However, continuous monitoring of pressure drop through the use of a differential pressure gauge or a transducer is the optimal solution. In summary, changing filters on hours is not maintenance effective, or cost effective.
3. Heat. If you’re driving along and you notice that your car engine is overheating, you would most likely stop. Most equipment owners won’t run an engine that is overheating. They know it’s going to cause problems. However, the same cannot be said about operators of hydraulic system.
Just as with a car, running an overheated engine is the quickest way to destroy hydraulic seals, hoses and other components. How hot is too hot? The answer depends on the viscosity of the oil in addition to the hydraulic components. Viscosity lessens with increasing temperature, so the answer is when the temperature is high enough to stop the oil lubricating as it should.
When it comes to hydraulic components, it’s worth noting that a vane pump needs more viscosity than a piston pump would. If you have a vane pump in your hydraulic system, then you’ll want at least 25 centistokes to be maintained.
Temperatures over 82°C will cause damage to seals and hoses in addition to accelerating the oil’s degradation. Never allow your hydraulic system to operate above 82°C with a viscosity lower than 10 centistokes.
4. The wrong oil. The most important element of any hydraulic system is always the oil. It’s what keeps everything lubricated and it is also what transfers the power. With these two major tasks to handle, keeping an eye on viscosity is a must.
The viscosity of the oil is what will determine the temperature at which the system should be run. You may have heard this referred to as temperature operating window or TOW. A temperature that is too high will prevent the oil from flowing or lubricating as it should. Oil that has a viscosity that is too low will not deliver adequate lubrication either. Keeping an eye on this will also ensure that you power isn’t lost due to either internal leakage or mechanical friction.
You don’t want increased power consumption as it will cost you more. The best way to handle this is to check what your machines temperature operating window is and to ensure that your machine operates within that window at all times. We won’t go into how to do this here, as it’s rather complex, but it’s something that does need to be addressed.
5. Filter locations. There are two locations for filters that cause the most problems – the piston pump and motor case line and the pump inlet. You may have a strainer attached to the pump inlet to collect any ‘garbage’ in your oil, but this oil is being drawn from a reservoir, not somewhere where there should be any garbage.
The pump inlet is also positioned off the bottom, so there should not be a lot of dirt passing through. By placing filters here, it can affect whether you get maximum pump life. If there is any form of restricted intake, it can reduce the lifespan of the gear pump by as much as half. Hydraulic pumps are not built with ‘sucking’ in mind! The way to handle this is to remove any suction strainers or depth filters on either the pump inlet or the piston pump.
Applying these points should be helpful to any hydraulic system operators and should deliver methods to save yourself and your business great expense.
Until next time..
Keeping overheads low is a fundamental of good money management in business. When your supervisor tells you that the company are pulling in its purse strings and he wants you and your department to help, it’s might not always obvious as to how you can cut back on costs, in particular in this day and age of expensive parts and fuel.
One approach is to save on fluid. Although your hydraulic system may not even be leaking, if you could keep your oil in service longer than usual, whilst not putting your machine at risk of damage, then you know you’re going to be his favourite employee this month.
Here’s how to do it:
Keep it inside
The most important thing is not to waste it. Although you may have a couple of slow leaks that are on your list to be fixed at some point, they are costing you more as every day goes by. The price of oil might be lower than it was, but it’s still pricey. Solving leaks comes complete with a cost reduction. If you don’t attend to them, then you’re affecting your department’s economy.
Keep it responsive
Keeping your oil within optimal operating temperatures offers many advantages. For one, it’s going to have a longer life. By allowing it to get just 10 degrees warmer, it will not have an extended life according to Arrhenius's Law. There will be negative reactions including oxidation. This is caused by air entering the system and hydrolysis – the presence of water. The warmer the oil, the more you’ll suffer from these.
In order to illustrate this – consider what happens when you have cooking oil at home. You could pour it into a cup and leave it on the side. It will take a long time to change colour. However, if you put it into a frying pan and heat it as hot as you can, you’re soon going to have a pan of darkened oil.
Some oils have anti-oxidant additives added. In addition you may want to consider installing a heat exchanger, increasing the number of filters and magnetic plugs and even going so far as replacing any copper or brass tubings under circumstances where the pressure rating is more than 10 bar.
If you do opt to use magnetic plugs, then ensure that there is regular cleaning of them. Otherwise the particles may be dislodged by any oil surge and then they will be back circulating around your system and causing damage. In addition, using the magnetic plugs will help to reduce the work of the filter.
Keep the water out
Water can damage oil. It can also compromise any additives in it. Take ZDDP which is an anti-wear additive, add water to it and you’ll find that it’s completely unstable.
Keep it clean
It’s difficult to keep hydraulic oil clean. Every time you access the system there is a chance that it will collect dust particles. It’s also likely that particles are building up from wear inside the machine. Certain metals are worse than others when it comes to increasing how fast hydrolysis and oxidation happen. These metals include iron, copper, lead and zinc in addition to water. It’s also likely that particles will attach themselves to any additives in the oil, which will lead to depletion of the additives.
In summary, gaining extended longevity from your hydraulic oil comes from good maintenance; keeping your machine leak-free, keeping oil at optimal temperature and clean. Don’t change it until the oil has degraded or your additives have extensively depleted.
Performing maintenance often and well will keep you in the good books of your boss. There’s nothing better than good filtration and the prevention of impurities to keep the fluid clean. You may also want to look at your oil storage system prior to oil being entered into the system. For example, keeping oil barrels horizontal can protect them from water collecting near the bungs. It will also mean that the bung is kept wet and therefore will be more effective as an airtight seal.
Let us know how you get on and if you have tips to share on improving hydraulic system economy, do tell.
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.
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.
It’s no secret that hydraulic systems are sensitive to contamination from fluid or oil. Those that are kept clean and protected against the introduction of dirt or water, can run reliably. However, if any contamination is allowed to slip then there will be problems ahead.
Clearances are tight in hydraulic systems and the components such as cylinders, valves and pumps are markedly sensitive. Even a small foreign particle is likely to cause a problem.
Although the layout of hydraulic systems differs from system to system, there are of course the basic elements that are common across the board. For example, the hydraulic reservoir can become home to contaminants or there can be a filtration system employed to clean the fluid.
There is also the pump. Depending on whether a gear pump is in use or a vane or piston pipe that generally have tighter clearances is installed will depend on how much contamination your machine will withstand.
Finally, the flow control valves range in sensitivity, with servo-controlled systems being the most particular. The simpler setups that involve directional or check valves will handle more contamination before failing.
The smartest way to handle the risk and fallout from contamination is to develop a contamination control strategy. This should be built around:
· Control targets determined by your system design
· Detailed actions to ensure that your contamination control targets are met or exceeded
· Measurement by analysis of your oil to check if cleanliness targets are met
Let’s explore these further:
Cleanliness target development
Hydraulic systems suffer most from particular contamination and water contamination. However, heat and air can also have detrimental effects on them. Particles within the range of 1 to 10 microns ideally need to be captured. To put this into perspective, 3 microns is around the size of a human hair thickness, but this sized particle can bring down a hydraulic system fast. Clearances between moving parts in systems are typically made for between 1 and 5 microns to pass, but it’s not always going to be the case.
How to exclude particles and moisture
Once a target for cleanliness has been identified, then it’s important to take action to ensure that these goals can be achieved. The most important areas to look at now are the exclusion of contamination and its removal. Exclusion is focused on ensuring that contamination doesn’t get into the system and removal is built around the use of filters. Keep in mind that removing contaminations can be very expensive, so a strong focus should be put onto exclusion.
Looking at how to exclude particles and contamination involves checking every step of the lubrication oil process. This includes when you receive the oil, how it’s handled, stored, dispensed and its use in the system. It’s a surprising but disappointing fact that many oils that come into a plant can actually be too dirty to use without initially going through a filtration process. Some engineers recommend that new hydraulic oil should go through a filtering process at least 5 times before they are used.
Now that you have your exclusion system and other contamination control systems in place, it’s important to measure how effective your process is. Use the ISO 4406:99 system to check to what degree your hydraulic fluid is contaminated with particles. Take samples from the machine, preferably from the actuator return lines. You may also take them from the reservoir, but taking them from there will not provide you with information as to what’s going on in the rest of the system.
In summary, the reliability of any hydraulic system is dependent upon its levels of contamination. By keeping it clean you can decrease problems. Once any hydraulic system is contaminated it will lead to trouble and expense. It’s possible to control contamination in the most challenging of environments by using this simple three step process.
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